AMMAR AMINE
Professeur des universités
Professeur des Universités
DIPPE - Durabilité, Ingénierie des Procédés et Physique des Ecoulements
Amine Ammar is a full Professor on Computational Mechanics at Arts & Métiers (French high school of engineering) - LAMPA. He has obtained his PhD Thesis in 2001 at Paris VI university - ENS Cachan, the title is “Polymer flow induced crystallization, Application to injection molding". In the year 2006 he has obtained his French degree to supervise research (HdR); specialty: mechanics. It was about " the solution of kinetic theory models related to complex fluids". On 2009 he has obtained the Scientific prize of the European Association of Material Forming awarded in the 12th Esaform conference and the French Jean Mandel prize awarded in the 19th CFM conference. His research has been made on different topics: model reduction of PDE resolution, proper generalized decomposition, kinetic theory of polymers and suspensions, short reinforced fiber composite processing. He is author of 130 scientific works published in international journals. He has supervised more than 20 PhD.
Rock salt, owing to its viscoplastic behavior and structural integrity under high pressure, is a promising candidate for safe and large-scale underground energy storage. This study presents a comprehensive numerical framework for modeling the viscoplastic deformation of rock salt, accounting for bot…
Finite Elements in Analysis and Design. 2025;252(1)
DOI : 10.1016/j.finel.2025.104438
Nanoindentation tests are an effective experimental approach to characterize the effects on local mechanical properties of epoxy resins undergoing thermo-oxidative ageing. However, there is currently no physical model capable of accurately representing these effects. In this work, we propose a hybri…
Computational Materials Science. 2025;259:114166.
DOI : 10.1016/j.commatsci.2025.114166
Applications in Engineering Science. 2025;23:100240.
DOI : 10.1016/j.apples.2025.100240
This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are …
International Journal of Material Forming. 2025;42:15.
DOI : 10.1007/s12289-025-01904-9
This work offers a detailed examination of the phase field approach for modeling brittle fracture, emphasizing its theoretical foundations, mathematical descriptions, and computational strategies. Central to our discussion is an in-depth analysis of strain energy decomposition methods integral to ph…
Advanced Modeling and Simulation in Engineering Sciences. 2025;12
DOI : 10.1186/s40323-025-00295-5
Most commercial software used to simulate the injection molding process of semi-crystalline thermoplastic polymers do not explicitly take into account the polymer crystallization, which could lead to errors in the estimations of filling as well as warpage and shrinkage. This is mainly due to the com…
International Journal of Advanced Manufacturing Technology. 2024;133(11-12):5243-5270.
DOI : 10.1007/s00170-024-13961-6
Trajectory planning aims at computing an optimal trajectory through the minimization of a cost function. This paper considers four different scenarios: (i) the first concerns a given trajectory on which a cost function is minimized by a acting on the velocity along it; (ii) the second considers traj…
Advanced Modeling and Simulation in Engineering Sciences. 2024;11(1):1-19.
DOI : 10.1186/s40323-024-00266-2
Knowing the thermo-mechanical history of a part during its processing is essential to master the final properties of the product. During forming processes, several parameters can affect it. The development of a surrogate model makes it possible to access history in real time without having to resort…
International Journal of Material Forming. 2024;17(16)
DOI : 10.1007/s12289-024-01812-4
Nowadays, numerical simulation, such as computational fluid dynamics (CFD), has become an essential tool for scientific investigation and analysis of complex systems in engineering allowing high-fidelity Navier-Stokes resolution for realistic turbulent flows which cannot be solved analytically. Howe…
Mechanics & Industry. 2024;25:31.
DOI : 10.1051/meca/2024023
This paper reports the results of an experimental investigation of graphene particle suspensions in lubricating oil, ethylene glycol and glycerol-based fluids. Graphene particles of different specific surface area show variation in the viscosity depending on the shear rate and the temperature. The l…
Journal of Thermal Analysis and Calorimetry. 2023;148(21):11455-11465.
DOI : 10.1007/s10973-023-12498-2
In the present work, the general and well-known model reduction technique, PGD (Proper Generalized Decomposition), is used for parametric analysis of thermo-elasticity of FGMs (Functionally Graded Materials). The FGMs have important applications in space technologies, especially when a part undergoe…
Materials. 2023;16(4):1-23.
DOI : 10.3390/ma16041753
Many composite manufacturing processes employ the consolidation of pre-impregnated preforms. However, in order to obtain adequate performance of the formed part, intimate contact and molecular diffusion across the different composites’ preform layers must be ensured. The latter takes place as soon a…
Polymers. 2023;15(6):1449.
DOI : 10.3390/polym15061449
Inherited myopathies are a group of disease, which, although distinct from a genetic and prognostic point of view, can lead to non-specific clinical pictures due to phenotypic overlap. Acquired immuno-mediated myopathies may also pose the problem of clinically accurate etiological orientation. The a…
Revue Neurologique. 2023;179(1-2):61-80.
DOI : 10.1016/j.neurol.2022.12.002
Nowadays data is acquiring an indisputable importance in every field including engineering. In the past, experimental data was used to calibrate state-of-the art models. Once the model was optimally calibrated, numerical simulations were run. However, data can offer much more, playing a more importa…
Computers & Mathematics with Applications. 2022;127:12-24.
DOI : 10.1016/j.camwa.2022.09.026
The computational cost of high-fidelity injection molding simulations has been growing in the past years making it more and more challenging to use them for performing analyses such as optimizations or uncertainty quantification. Surrogate modeling offers a cheaper way to realize such studies and ha…
International Journal of Material Forming. 2022;15(6):2-19.
DOI : 10.1007/s12289-022-01717-0
This study investigates the double-diffusive natural convection of the non-Newtonian Casson fluid in a square cavity based on the original viscoplastic stress model without simplification. Therefore, yield stress plays an essential role in understanding fluid behavior. The finite element approach pr…
International Journal of Mechanical Sciences. 2022;236:107754.
DOI : 10.1016/j.ijmecsci.2022.107754
Ti-6Al-4V titanium is considered a difficult-to-cut material used in critical applications in the aerospace industry requiring high reliability levels. An appropriate selection of cutting conditions can improve the machinability of this alloy and the surface integrity of the machined surface, includ…
Journal of Manufacturing and Materials Processing. 2022;6(3):58.
DOI : 10.3390/jmmp6030058
A domain decomposition technique combined with an enhanced geometry mapping based on the use of NURBS is considered for solving parametrized models in complex geometries (non simply connected) within the so-called proper generalized decomposition (PGD) framework, enabling the expression of the solut…
Advanced Modeling and Simulation in Engineering Sciences. 2022;9:2.
DOI : 10.1186/s40323-022-00216-w
Entropy. 2022;24(6):782.
DOI : 10.3390/e24060782
In the context of parametric surrogates, several nontrivial issues arise when a whole curve shall be predicted from given input features. For instance, different sampling or ending points lead to non-aligned curves. This also happens when the curves exhibit a common pattern characterized by critical…
Frontiers in Materials. 2022;9:904707.
DOI : 10.3389/fmats.2022.904707
In the automotive industry, building parametric surrogate models is a fundamental tool to evaluate, in real time, the performance of newly designed car components. Such models allow to compute any Quantity of Interest —QoI—, such as a specific safety protocol index, for any choice of material and/or…
Heliyon. 2022;8(12):e12397.
DOI : 10.1016/j.heliyon.2022.e12397
Two main problems are studied in this article. The first one is the use of the extrusion process for controlled thermo-mechanical degradation of polyethylene for recycling applications. The second is the data-based modelling of such reactive extrusion processes. Polyethylenes (high density polyethyl…
Polymers. 2022;14(4):800.
DOI : 10.3390/polym14040800
Solutions of partial differential equations can exhibit multiple time scales. Standard discretization techniques are constrained to capture the finest scale to accurately predict the response of the system. In this paper, we provide an alternative route to circumvent prohibitive meshes arising from …
Advanced Modeling and Simulation in Engineering Sciences. 2021;8(26):1-22.
DOI : 10.1186/s40323-021-00211-7
Abstract Solutions of partial differential equations can exhibit multiple time scales. Standard discretization techniques are constrained to capture the finest scale to accurately predict the response of the system. In this paper, we provide an alternative route to circumvent prohibitive meshes aris…
Advanced Modeling and Simulation in Engineering Sciences. 2021;8(1):267-293.
DOI : 10.1186/s40323-021-00211-7
The use of mesh-based numerical methods for a 3D elasticity solution of thick plates involves high computational costs. This particularly limits parametric studies and material distribution design problems because they need a large number of independent simulations to evaluate the effects of materia…
Materials. 2021;14(21):6660.
DOI : 10.3390/ma14216660
A promising advance of bioengineering consists in the development of micro-nanoparticles as drug delivery vehicles injected intravenously or intraarterialy for targeted treatment. Pro cient functioning of drug carries is conditioned by a reliable prediction of pharma- cokinetics in human as well as …
Journal of Mechanics in Medicine and Biology. 2021;21(8)
DOI : 10.1142/S0219519421500627
Space separation within the Proper Generalized Decomposition—PGD—rationale allows solving high dimensional problems as a sequence of lower dimensional ones. In our former works, different geometrical transformations were proposed for addressing complex shapes and spatially non-separable domains. Eff…
Advanced Modeling and Simulation in Engineering Sciences. 2021;8(1)
DOI : 10.1186/s40323-021-00208-2
The effect of shear flow on spherical nanoparticles (NPs) migration near a liquid–liquid interface is studied by numerical simulation. We have implemented a compact model through which we use the diffuse interface method for modeling the two fluids and the molecular dynamics method for the simulatio…
Entropy. 2021;23(9):1143.
DOI : 10.3390/e23091143
The dynamic viscosity and rheological properties of two different non-aqueous graphene nano-plates-based nanofluids are experimentally investigated in this paper, focusing on the effects of solid volume fraction and shear rate. For each nanofluid, four solid volume fractions have been considered ran…
Entropy. 2021;23(8):979.
DOI : 10.3390/e23080979
The study of artificial microparticles (capsules and vesicles) has gained a growing interest with the emergence of bioengineering. One of their promoting applications is their use as therapeutic vectors for drug delivery, when capsules and vesicles release their capacity in a targeted environment. T…
J Biomech Eng. 2021..
DOI : 10.1115/1.4049955
Most commercial softwares simulating casting process use a scalar field to quantify the shrinkage on final parts. The repartition of this scalar is used to localize shrinkage in the part. In this work, the objective is to use a new approach to predict morphological information about size and shape o…
International Journal of Material Forming. 2021;14(5):885-899.
DOI : 10.1007/s12289-020-01602-8
The description of a physical problem through a model necessarily involves the introduction of parameters. Hence, one wishes to have a solution of the problem that is a function of all these parameters: a parametric solution. However, the construction of such parametric solutions exhibiting localiza…
Mathematics and Computers in Simulation. 2021;194:36-63.
DOI : 10.1016/j.matcom.2021.11.010
Numerical simulations and parametric studies of notched rectangular specimens subjected to dynamic tensile loads were performed. The simulations were based on two-dimensional finite element analysis to predict the brittle fracture path using the phase-field approach. The parametric studies investiga…
Comptes Rendus. Mécanique. 2020;348(8-9):729-744.
DOI : 10.5802/crmeca.52
Journal of Infection. 2020;81(5):816-846.
DOI : 10.1016/j.jinf.2020.07.028
Finite Elements in Analysis and Design. 2020;177:103419.
DOI : 10.1016/j.finel.2020.103419
A generic methodology to deal with the mechanics of beams and shafts with cracks is presented. The elastic energy of the system under static loading is written in a comprehensive manner to remarkably reduce the 3D computations indispensable to the identification of the crack breathing mechanism. Wit…
International Journal for Numerical Methods in Engineering. 2020;121(15):3362-3381.
DOI : 10.1002/nme.6361
This paper analyzes the ability of different machine learning techniques, able to operate in the low-data limit, for constructing the model linking material and process parameters with the properties and performances of parts obtained by reactive polymer extrusion. The use of data-driven approaches …
Fluids. 2020;5(2):94.
DOI : 10.3390/fluids5020094
Composite manufacturing processes usually proceed from preimpregnated preforms that are consolidated by simultaneously applying heat and pressure, so as to ensure a perfect contact compulsory for making molecular diffusion possible. However, in practice, the contact is rarely perfect. This results i…
International Journal for Numerical Methods in Engineering. 2020;121:5256-5274.
DOI : 10.1002/nme.6448
The present work aims at proposing a new methodology for learning reduced models from a small amount of data. It is based on the fact that discrete models, or their transfer function counterparts, have a low rank and then they can be expressed very efficiently using few terms of a tensor decompositi…
Comptes Rendus. Mécanique. 2019;347(11):780-792.
DOI : 10.1016/j.crme.2019.11.003
Solutions of partial differential equations could exhibit a multiscale behavior. Standard discretization techniques are constraints to mesh up to the finest scale to predict accurately the response of the system. The proposed methodology is based on the standard proper generalized decomposition rati…
International Journal for Numerical Methods in Engineering. 2019;120(6):727-747.
DOI : 10.1002/nme.6154
This work aims at proposing a new procedure for parametric problems whose separated representation has been considered difficult, or whose SVD compression impacted the results in terms of performance and accuracy. The proposed technique achieves a fully separated representation for layered domains w…
Computer Methods in Applied Mechanics and Engineering. 2019;Volume 354,:Pages 802-819.
DOI : 10.1016/j.cma.2019.05.047
The present work aims at performing a molecular dynamics modeling of suspensions composed of flexible linear molecules. Molecules are represented by a series of connected beads, whose dynamics is governed by three potentials: the extension potential affecting the elongation of segments connecting co…
Comptes Rendus. Mécanique. 2019;347(11):743-753.
DOI : 10.1016/j.crme.2019.11.001
Compressed sensing is a signal compression technique with very remarkable properties. Among them, maybe the most salient one is its ability of overcoming the Shannon–Nyquist sampling theorem. In other words, it is able to reconstruct a signal at less than 2Q samplings per second, where Q stands for …
Computational Mechanics. 2019;64(5):1259-1271.
DOI : 10.1007/s00466-019-01703-5
This study aims at investigating numerically the Rayleigh-Bénard Convection (RBC) in viscoplastic fluids. A Casson fluid is considered in a bidimensional square cavity heated from below. The effects of the dimensionless yield stress, the Bingham number Bn, on the heat transfer and motion is investig…
International Journal of Thermal Sciences. 2018;127:79-90.
DOI : 10.1016/j.ijthermalsci.2018.01.016
This article presents an efficient numerical strategy to simulate the damage in composite laminates under low velocity impact. The proposed method is based on a separated representation of the solution in the context of the Proper Generalized Decomposition (PGD). This representation leads to an impo…
Computers & Structures. 2018;199:34-45.
DOI : 10.1016/j.compstruc.2018.01.012
When addressing the flow of concentrated suspensions composed of rods, dense clusters are observed. Thus, the adequate modelling and simulation of such a flow requires addressing the kinematics of these dense clusters and their impact on the flow in which they are immersed. In a former work, we addr…
Continuum Mechanics and Thermodynamics. 2018..
DOI : 10.1007/s00161-018-0659-1
The numerical modelling of the behaviour of materials at the microstructural scale has been greatly developed over the last two decades. Unfortunately, conventional resolution methods cannot simulate polycrystalline aggregates beyond tens of loading cycles, and they do not remain quantitative due to…
Comptes Rendus. Mécanique. 2018;20.
The requirements for advanced numerical computations are very high when studying the multiscale behavior of heterogeneous structures such as composites. For the description of local phenomena taking place on the microscopic scale, the computation must involve a fine discretization of the structure. …
Mathematics and Computers in Simulation. 2018;144:162-181.
DOI : 10.1016/j.matcom.2017.07.010
Describing the orientation state of the particles is often critical in fibre suspension applications. Macroscopic descriptors, the so-called second-order orientation tensor (or moment) leading the way, are often preferred due to their low computational cost. Closure problems however arise when evolu…
Computer Modeling in Engineering and Sciences. 2018;117(3):367-386.
DOI : 10.31614/cmes.2018.04278
Sparse model identification by means of data is especially cumbersome if the sought dynamics live in a high dimensional space. This usually involves the need for large amount of data, unfeasible in such a high dimensional settings. This well-known phenomenon, coined as the curse of dimensionality, i…
Complexity. 2018;2018:1-11.
DOI : 10.1155/2018/5608286
Dans ce papier, nous présentons brièvement une approche basée sur la PGD pour réduire les coûts de calcul lors de la simulation du comportement d’une plaque composite sous sollicitation dynamique. Le cas de l’impact basse vitesse avec endommagement (délaminage et fissuration matricielle) est présent…
2017..
Several studies showed that thin-plies composite laminates apparently exhibit higher strength than its counterpart using thicker plies. In this work, a high-resolution numerical discretization based on the use of in-plane-out-of-plane separated representations within the Proper Generalized Decomposi…
Composite Structures. 2017;12.
DOI : 10.1016/j.compstruct.2017.03.083
The development of computation means has allowed the simulation of complex mechanical problems. The first simulations of manufacturing processes at the microstructure scale, namely in the field of machining, have recently emerged. In this study, and on the basis of previous research, a novel approac…
Finite Elements in Analysis and Design. 2017;137:43-55.
DOI : 10.1016/j.finel.2017.08.002
Purpose : The purpose of this paper is to analyze two-dimensional steady-state Rayleigh–Bénard convection within rectangular enclosures in different aspect ratios filled with yield stress fluids obeying the Herschel–Bulkley model. Design/methodology/approach : In this study, a numerical method based…
Engineering Computations. 2017;19.
Forming processes usually involve irreversible plastic transformations. The calculation in that case becomes cumbersome when large parts and processes are considered. Recently Model Order Reduction techniques opened new perspectives for an accurate and fast simulation of mechanical systems. In some …
2016;6.
This study proposes to simulate the deep drawing on carbon woven composites in order to reduce the manufacturing cost and waste of composite material during the stamping process, The multi-scale anisotropic approach of woven composite was used to develop a finite element model for simulating the ori…
Applied Composite Materials. 2016;23(3):461-476.
DOI : 10.1007/s10443-015-9468-x
Enhancing thermal conductivity of simple fluids is of major interest in numerous applicative systems. One possibility of enhancing thermal properties consists of dispersing small conductive particles inside. However, in general, aggregation effects occur and then one must address systems composed of…
Entropy. 2016;19:1-15.
DOI : 10.3390/e19010019
The Langevin function is defined by L (x ) = coth (x ) −1 /x . Its inverse is useful for many applications and especially for polymer science. As the inverse exact expression has no analytic representation, many ap- proximations have been established. The most famous approximation is the one traditi…
Journal of Non-Newtonian Fluid Mechanics. 2016;:1-5.
DOI : 10.1016/j.jnnfm.2016.02.008
Permeability is the fundamental macroscopic material property needed to quantify the flow in a fibrous medium viewed as a porous medium. Composite processing models require the permeability as input data to predict flow patterns and pressure fields. In a previous work, the expressions of macroscopic…
International Journal of Material Forming. 2016;1-10.
DOI : 10.1007/s12289-016-1300-0
The aim of this study is to develop a new numerical cutting model that includes fluid structure interaction and to take into account heat transfer between the water-jet, the workpiece and the chip. This has been achieved using a CEL (Coupled–Eulerian–Lagrangian) technique, an algorithm has been deve…
Finite Elements in Analysis and Design. 2016;108:1-8.
DOI : 10.1016/j.finel.2015.09.003
The numerical solution of the Chemical Master Equation (CME) governing gene regulatory networks and cell signaling processes remains a challenging task due to its complexity, exponentially growing with the number of species involved. When considering separated representations of the probability dist…
Biological Systems: Open Access. 2016;5(1):1-12.
DOI : 10.4172/2329-6577.1000155
Understanding the physics of chip formation in machining operations is often difficult due to the complexity of the phenomena involved, such as the extreme and complex loading conditions that occur in the cutting zone. In order to model the machining process, it is necessary to use a constitutive be…
International Journal of Advanced Manufacturing Technology. 2016;1-11.
DOI : 10.1007/s00170-016-9476-5
This study aims at the developing of a numerical method for the resolution of the finite element for nonlinear viscoplastic problems. For this, two ideas are used. The first is to maintain a constant stiffness matrix [4] to do only one factorization. The second con-cerns the use of a model reduction…
2015..
Les modélisations numériques des matériaux à l’échelle de la microstructure se sont fortement développées au cours des deux dernières décennies. Malheureusement, les méthodes de résolution classiques ne permettent pas de simuler les agrégats polycristallins au-delà de quelques dizaines de cycles à c…
2015;7.
Les modélisations numériques des matériaux à l'échelle de la microstructure se sont fortement développées au cours des deux dernières décennies. Malheureusement, les méthodes de résolution classiques ne permettent pas de simuler les agrégats polycristallins au-delà de quelques dizaines de cycles à c…
2015..
La simulation des structures périodiques contenant un grand nombre de cellules élémentaires mais pas suffisamment pour pouvoir utiliser des méthodes d'homogénéisation pose des difficultés. Nous proposons ici une technique de décomposition de domaines basée sur la PGD. L'idée est de séparée les échel…
2015..
The motion of an ellipsoidal particle immersed in a flow of a Newtonian fluid was obtained in the pioneering work of Jeffery in 1922. Suspensions of industrial interest usually involve particles with a variety of shapes. Moreover, suspensions composed of rods (a limit case of an ellipsoid) aggregate…
2015..
La prédiction du comportement des structures composites sous chargements dynamiques nécessite l'utilisation de maillages extrêmement fins, pour pouvoir représenter leur dégradation progressive. Le comportement non-linéaire des composites stratifiés met en jeu des phénomènes à la fois locaux et à l'é…
2015..
The fine description of complex fluids can be carried out by describing the evolution of each individual constituent (e.g. each particle, each macromolecule, etc.). This procedure, despite its conceptual simplicity, involves many numerical issues, the most challenging one being that related to the c…
Communications in Computational Physics. 2015;17(4):975-1006.
DOI : 10.4208/cicp.2014.m326
In this work, we begin by considering the qualitative modeling of biological regulatory systems using process hitting, from which we define its probabilistic counterpart by considering the chemical master equation within a kinetic theory framework. The last equation is efficiently solved by consider…
Entropy. 2015;17(4):1896-1915.
DOI : 10.3390/e17041896
Forming processes usually involve irreversible plastic transformations. The calculation in that case becomes cumbersome when large parts and processes are considered. Recently Model Order Reduction techniques opened new perspectives for an accurate and fast simulation of mechanical systems, however …
2015;651-653:1285-1293.
Nanocomposites allow for a significant enhancement of functional properties, in particular electrical conduction. In order to optimize materials and parts, predictive models are required to evaluate particle distribution and orientation. Both are key parameters in order to evaluate percolation and t…
Advanced Modeling and Simulation in Engineering Sciences. 2015;2(23):1-24.
DOI : 10.1186/s40323-015-0044-6
Purpose – The purpose of this paper is to focus on the advanced solution of the parametric non-linear model related to the Rayleigh-Benard laminar flow involved in the modeling of natural thermal convection. This flow is fully determined by the dimensionless Prandtl and Rayleigh numbers. Thus, if on…
International Journal of Numerical Methods for Heat and Fluid Flow. 2015;25(6):1252-1281.
DOI : 10.1108/HFF-06-2014-0196
This paper presents experimental results concerning the machinability of the titanium alloy Ti17 with and without high-pressure water jet assistance (HPWJA) using uncoated WC/Co tools. For this purpose, the influence of the cutting speed and the water jet pressure on the evolution of tool wear and c…
Precision Engineering. 2015;42:294-301.
DOI : 10.1016/j.precisioneng.2015.06.004
Purpose – The purpose of this paper is to compute flow effects of the transition from adherence-to-slip in two-dimensional flows, for a polymer melt obeying a memory-integral viscoelastic equation, in isothermal and non-isothermal cases. Design/methodology/approach – Temperature dependence is expres…
Engineering Computations. 2015;32(8):2318-2342.
DOI : 10.1108/EC-02-2014-0039
L'analyse du comportement mécanique des matériaux entraîne de nombreuses difficultés du point de vue numérique. Dans ce travail, nous allons nous focaliser sur l'une d'entre elles, celle associée à la simulation transitoire du comportement mécanique quand l'intervalle temporel d'intérêt est substant…
Comptes Rendus. Mécanique. 2015;343(4):247-263.
DOI : 10.1016/j.crme.2015.02.002
The use of cohesive zone models is an efficient way to treat the damage, especially when the crack path is known a priori. This is the case in the modeling of delamination in composite laminates. However, the simulations using cohesive zone models are expensive in a computational point of view. When…
International Journal for Numerical Methods in Engineering. 2014;99(13):1000-1022.
DOI : 10.1002/nme.4732
It is now well established that separated representations built with the help of Proper Generalized Decomposition (PGD) can drastically reduce computational costs associated with solution of a wide variety of problems. However, it is still an open question to know if separated representations can be…
Computer Methods in Applied Mechanics and Engineering. 2014;273:56-76.
DOI : 10.1016/j.cma.2014.01.019
Optimization of manufacturing processes or structures involves the optimal choice of many parameters (process parameters, material parameters or geometrical parameters). Usual strategies proceed by defining a trial choice of those parameters and then solving the resulting model. Then, an appropriate…
Computer Methods in Applied Mechanics and Engineering. 2014;268:178-193.
DOI : 10.1016/j.cma.2013.09.003
We extend the Maffettone–Minale model by including non-elliptical shapes of dispersed particles, a new family of internal forces controlling particle deformations, and particle–particle interactions. The last extension is made by transposing the way the chain-chain interactions are mathematically ex…
Journal of Non-Newtonian Fluid Mechanics. 2014;212:1-12.
DOI : 10.1016/j.jnnfm.2014.07.005
Simulation of all phenomena taking place in a surgical procedure is a formidable task that involves, when possible, the use of supercomputing facilities over long time periods. However, decision taking in the operating room needs for fast methods that provide an accurate response in real time. To th…
Journal of Computational Surgery. 2014;1(1):1-14.
DOI : 10.1186/2194-3990-1-1
Micro-macro simulations of polymeric solutions rely on the coupling between macroscopic conservation equations for the fluid flow and stochastic differential equations for kinetic viscoelastic models at the microscopic scale. In the present work we introduce a novel micro-macro numerical approach, w…
Journal of Non-Newtonian Fluid Mechanics. 2013;201:29-38.
DOI : 10.1016/j.jnnfm.2013.07.004
This article presents the results of an experimental study on the Ti17 titanium alloy, which was carried out to analyze tool wear and the degradation mechanisms of an uncoated tungsten carbide tool insert. Two machining conditions, roughing and finishing, have been studied under different lubricatio…
Wear. 2013;305(1-2):228-237.
DOI : 10.1016/j.wear.2013.06.018
When suspensions involving rigid rods become too concentrated, standard dilute theories fail to describe their behavior. Rich microstructures involving complex clusters are observed, and no model allows describing its kinematics and rheological effects. In previous works the authors propose a first …
Entropy. 2013;15(7):2805-2832.
DOI : 10.3390/e15072805
Titanium alloys are known for their excellent mechanical properties, especially at high temperature. But this specificity of titanium alloys can cause high cutting forces as well as a significant release of heat that may entail a rapid wear of the cutting tool. To cope with these problems, research …
Key Engineering Materials. 2013;554-557:1961-1966.
DOI : 10.4028/www.scientific.net/KEM.554-557.1961
Les méthodes de représentation à variables séparées permettent de réduire de façon drastique les coûts numériques associés à la résolution d'une grande variété de problèmes. Cependant, l'efficacité des décompositions espace-temps pour les problèmes d'évolution de type hyperbolique reste à démontrer.…
2013..
Smoluchowski kinetic equation governing the time evolution of the pair correlation function of rigid sphericalparticles suspended in a Newtonian fluid is extended to include particle migration. The extended kinetic equation takes into account three types of forces acting on the suspended particles: …
Rheologica Acta. 2013;52(6):557-577.
DOI : 10.1007/s00397-013-0705-7
Proper Generalized Decomposition (PGD) is a method which consists in looking for the solution to a problem in a separate form. This approach has been increasingly used over the last few years to solve mathematical problems. The originality of this work consists in the association of PGD with a spect…
Applied Mathematics and Computation. 2013;219(15):8145-8162.
DOI : 10.1016/j.amc.2013.02.022
In this paper, we investigate ability of proper generalized decomposition (PGD) to solve transient elastodynamic models in space-time domain. Classical methods use time integration schemes and an incremental resolution process. We propose here to use standard time integration methods in a non-increm…
Computer Methods in Applied Mechanics and Engineering. 2013;255:67-88.
DOI : 10.1016/j.cma.2012.11.003
This papers addresses two issues usually encountered when simulating thermal processes in forming processes involving tape-type geometries, as is the case of tape or tow placement, surface treatments, ... The first issue concerns the necessity of solving the transient model a huge number of times be…
International Journal of Thermal Sciences. 2013;65:148-157.
DOI : 10.1016/j.ijthermalsci.2012.10.017
Modeling frameworks bring structure and analysis tools to large and non-intuitive systems but come with certain inherent assumptions and limitations, sometimes to an inhibitive extent. By building bridges in existing models, we can exploit the advantages of each, widening the range of analysis possi…
Computational Methods in Systems Biology. 2013;8130:50-63.
DOI : 10.1007/978-3-642-40708-6_5
In this paper we are addressing a new paradigm in the field of simulation-based engineering sciences (SBES) to face the challenges posed by current ICT technologies. Despite the impressive progress attained by simulation capabilities and techniques , some challenging problems remain today intractabl…
Archives of Computational Methods in Engineering. 2013;20(1):31-59.
DOI : 10.1007/s11831-013-9080-x
The morphology influencing rheological properties of suspensions of rigid spheres constitutes the flow induced collective ordering of the spheres characterized by two or more sphere distribution functions. When the rigid spheres are replaced by rigid fibers, the collective order in the position of t…
Journal of Non-Newtonian Fluid Mechanics. 2013;200:17-33.
DOI : 10.1016/j.jnnfm.2012.10.009
This paper focuses on the non-incremental solution of transient coupled non-linear models, in particular the one related to the Rayleigh-Benard flow problem that models natural thermal convection. For this purpose we are applying the so-called Proper Generalized Decomposition that proceeds by perfor…
Journal of Non-Newtonian Fluid Mechanics. 2013;200:65-78.
DOI : 10.1016/j.jnnfm.2012.11.007
The aim of this study is to apply proper generalized decomposition (PGD) to solve mixed-convection problems with and without mass transport in a two dimensional lid-driven cavity. PGD is an iterative reduced order model approach which consists of solving a partial differential equation while seeking…
Numerical Heat Transfer, Part B Fundamentals. 2013;63(1):18-43.
DOI : 10.1080/10407790.2012.724991
The numerical solution of the chemical master equation (CME) governing gene regulatory networks and cell signaling processes remains a challenging task owing to its complexity, exponentially growing with the number of species involved. Although most of the existing techniques rely on the use of Mont…
International Journal for Numerical Methods in Biomedical Engineering. 2012;28(9):960-973.
DOI : 10.1002/cnm.2476
This work addresses the recurrent issue related to the existence of reduced bases related to the solution of parametric models defined in evolving domains. In this first part of the work, we address the case of decoupled kinematics, that is, models whose solution does not affect the domain in which …
International Journal for Numerical Methods in Engineering. 2012;93(8):887-904.
DOI : 10.1002/nme.4413
A direct modeling of colloidal suspensions consists of calculating trajectories of all suspended objects. Due to the large time computing and the large cost involved in such calculations, we consider in this paper another route. Colloidal suspensions are described on a mesoscopic level by a distribu…
Rheologica Acta. 2012;51(6):527-543.
DOI : 10.1007/s00397-011-0609-3
Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics. 2012;19(5-7):591-617.
DOI : 10.3166/ejcm.19.591-617
The prediction of microstructure evolution during passive mixing is of major interest in order to qualify and quantify mixing devices as well as to predict the final morphology of the resulting blend. Direct numerical simulation fails because of the different characteristic lengths of the microstruc…
International Journal of Material Forming. 2012;5(1):73-81.
DOI : 10.1007/s12289-011-1037-8
The dynamics of phase transition in a binary mixture occurring during a quench is studied taking into account composition fluctuations by solving Langer's equation in a domain composed of a certain number of micro-domains. The resulting Langer's equation governing the evolution of the distribution f…
Modelling and Simulation in Materials Science and Engineering. 2012;20(1)
DOI : 10.1088/0965-0393/20/1/015007
L'objectif de ce travail est d'appliquer la méthode Proper Generalized Decomposition (PGD) pour résoudre les équations de Navier-Stokes. Par cette technique la solution est recherchée comme une somme de produits tensoriels de chacune des variables du problème (espace, temps ...). La méthode sera app…
2011..
L'objectif principal de cet article est de présenter les nouveaux développements d'outils et méthodes de simulations numériques destinés à comprendre et optimiser le fonctionnement d'une pompe Moineau métallique. Cette étude se décompose en deux temps : la première partie porte sur la mise au point …
2011..
We review the foundations and applications of the proper generalized decomposition (PGD), a powerful model reduction technique that computes a priori by means of successive enrichment a separated representation of the unknown field. The computational complexity of the PGD scales linearly with the di…
Journal of Non-Newtonian Fluid Mechanics. 2011;166(11):578-592.
In this work, the PGD method will be considered for solving some problems of fluid mechanics by looking for the solution as a sum of tensor product functions. In the first stage, the equations of Stokes and Burgers will be solved. Then, we will solve the Navier-Stokes problem in the case of the lid-…
Journal of Computational Physics. 2011;230(4):1387-1407.
DOI : 10.1016/j.jcp.2010.11.010
Le mélange de fluides immiscibles est fréquemment utilisé dans de nombreuses applications industrielles. Une approche directe de la représentation de cette interface est impossible du fait de la différence de taille caractéristique entre la microstructure et le procédé lui-même. Pour cette raison, l…
Rhéologie. 2011;20:44-52.
Today many problems in science and engineering remain intractable, in spite of the impressive progresses attained in mechanical modelling, numerical analysis, discretization techniques and computer science during the last decade, because their numerical complexity is simply unimaginable. We can dist…
2011..
Direct manufacturing technology using Selective Laser Sintering (SLS) on thermoplastic powders allows obtaining final parts in a short time, with classical polymer density and a high flexibility of shape and evolution of parts. The physical base of this process is the coalescence of grains, which in…
2011..
Models encountered in computational mechanics could involve many time scales. When these time scales cannot be separated, one must solve the evolution model in the entire time interval by using the finest time step that the model implies. In some cases, the solution procedure becomes cumbersome beca…
International Journal for Numerical Methods in Engineering. 2011;90(5):569-596.
DOI : 10.1002/nme.3331
Numerous models encountered in science and engineering remain nowadays , despite the impressive recent progresses attained in computational simulation techniques, intractable when the usual and well experienced discretization techniques are applied for their numerical simulation. Thus, different cha…
International Journal for Multiscale Computational Engineering. 2011;9:17-33.
DOI : 10.1615/IntJMultCompEng.v9.i1.30
In this work we analyze the possibilities of applying model reduction in the numerical modelling of forming processes. The use of such strategies allows impressive computing time savings in the numerical simulations of complex models without degrading the solution accuracy. For this purpose we apply…
2011..
Formulas expressing the extra stress tensor, $\boldsymbol\sigma$, in fiber suspensions in terms of microstructural state variables are derived by using two types of arguments: mechanical and thermodynamical. Results are compared for the distribution function ($\psi$) and the orientation tensor, $\ma…
Journal of Rheology. 2011;55:17-42.
DOI : 10.1122/1.3523538
This paper focuses on the efficient solution of models defined in high dimensional spaces. Those models involve numerous numerical challenges because of their associated curse of dimensionality. It is well known that in meshbased discrete models the complexity (degrees of freedom) scales exponential…
Mathematics and Computers in Simulation. 2010;81(4):791-810.
DOI : 10.1016/j.matcom.2010.07.015
De nos jours, l’amélioration des tests nos destructifs occupe un large espace dans les agendas des chercheurs. De plus, la demande des industriels du perfectionnement de ce genre de test est en perpétuelle augmentation, cherchant juger la qualité des pièces sans avoir à les détruire. Ceci est aussi …
2010..
Computational homogenization is nowadays one of the most active research topics in computational mechanics. Different strategies have been proposed, the main challenge being the computing cost induced by complex microstructures exhibiting nonlinear behaviors. Two quite tricky scenarios lie in (i) th…
Archives of Computational Methods in Engineering. 2010;17(4):373–391.
DOI : 10.1007/s11831-010-9051-4
Fine modeling of the structure and mechanics of materials from the nanometric to the micrometric scales uses descriptions ranging from quantum to statistical mechanics. Most of these models consist of a partial differential equation defined in a highly multidimensional domain (e.g. Schrodinger equat…
Computer Methods in Applied Mechanics and Engineering. 2010;199(25-28):1872-1880.
DOI : 10.1016/j.cma.2010.02.012
An efficient simulation of thermal and mechanical models involved in thermosetting composites forming needs to overcome some numerical difficulties related to: (i) the multi-scale behaviour; (ii) the complex geometries involved needing too many degrees of freedom; (iii) the large time intervals wher…
International Journal of Material Forming. 2010;3(Suppl 2):1339-1350.
DOI : 10.1007/s12289-009-0675-6
In this paper we review the possibilities associated with the use of Proper Generalized Decompositions for solving models established in highly multidimensional spaces. This technique has also been recently extended to problems that can be, under some circumstances, seen as multidimensional.…
Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics. 2010;19:53-64.
DOI : 10.3166/ejcm.19.53-64
Micro-macro models associate the coarse-grained molecular scale of the kinetic theory to the macroscopic scale of continuum mechanics. The conservation equations are solved along with the microscopic equation or the so-called Fokker-Planck equation. In this paper, a micro macro approach based on the…
Mathematics and Computers in Simulation. 2010;80(9):1936-1961.
DOI : 10.1016/j.matcom.2010.03.002
Separated representations based on finite sum decompositions constitute an appealing strategy for reducing the computer resources and the calculation costs by reducing drastically the number of degrees of freedom that the functional approximations involve (the number of degrees of freedom scale line…
International Journal for Numerical Methods in Engineering. 2010;81(5):637-659.
DOI : 10.1002/nme.2710
This paper revisits a powerful discretization technique, the Proper Generalized Decomposition—PGD, illustrating its ability for solving highly multidimensional models. This technique operates by constructing a separated representation of the solution, such that the solution complexity scales linearl…
Archives of Computational Methods in Engineering. 2010;17(4):327-350.
DOI : 10.1007/s11831-010-9049-y
Rheological model of fluids involving Brownian relaxation, reptation, diffusion, and scission–recombination processes as relaxation mechanisms is formulated. Numerical solution of a particular example of the model displays the S-shape form of the shear rate versus shear stress curves observed in wor…
Rheologica Acta. 2010;49(5):495-506.
DOI : 10.1007/s00397-009-0428-y
In this paper the coupling of a parabolic model with a system of local kinetic equations is analyzed. A space time separated representation is proposed for the global model (this is simply the radial approximation proposed by Pierre Ladeveze in the LATIN framework (Non-linear Computational Structura…
International Journal for Numerical Methods in Engineering. 2010;83(8-9):1114-1132.
DOI : 10.1002/nme.2794
Heterogeneous materials involve different length scales in their mechanical properties. Obviously a mechanical description taking into account all the microscopic details is impossible from a computational point of view except for parts of very small dimensions. The main aim of material homogenizati…
2010..
DOI : 10.1007/s12289-010-0913-y
If we are interested in solving a transient problem with the time scales ranging from the femto-second to the seconds, where the time scales are not separable, the time axis could be transformed into a 2D domain with a fast and a slow time scales, the finest one defined in a small interval and the s…
2010..
Description of complex materials, in particular complex fluids, involves numerous computational challenges. Today, atomistic descriptions are too expensive from the computational point of view, motivating that this kind of analysis is restricted to extremely small systems. The next scale introduces …
Communications in Mathematical Sciences. 2010;8(3):671-695.
In this paper we study the convergence of the well-known Greedy Rank-One Update Algorithm. It is used to construct the rank-one series solution for full-rank linear systems. The existence of the rank one approximations is also not new, but surprisingly the focus there has been more on the applicatio…
Archives of Computational Methods in Engineering. 2010;17(4):473-486.
DOI : 10.1007/s11831-010-9048-z
Inverse identification of complex fluid behaviors is a tricky task because sometimes there are several rheological parameters and the identification procedure itself is quite expensive from the computational time viewpoint. Standard inverse identification procedures solve the model for a choice of t…
Journal of Non-Newtonian Fluid Mechanics. 2010;165(23-24):1588-1601.
DOI : 10.1016/j.jnnfm.2010.08.006
La simulation efficace des modèles thermiques non-linéaires entraine un certain nombre de verrous associés : (i) au caractère multi-échelle en espace et temps ; (ii) aux grandes dimensions spatiales et temporelles ; (iii) au caractère non linéaire et aux termes sources décrivant différentes cinétiqu…
2009..
La résolution numérique d'écoulements turbulents nécéssite des maillages très fins et des temps de calculs très longs. Afin de réduire ces temps, on se propose d'utiliser la méthode de séparation de variable qui consiste à chercher la solution sous la forme d'une somme de produits de fonctions de ch…
2009..
Description of complex materials involves numerous computational challenges. Thus, the analysis of transient models needs for intensive computation. In some of our former works we proposed a technique based on the separated representation of the unknown field able to circumvent the curse of dimensio…
International Journal of Material Forming. 2009;2(S1):563-566.
DOI : 10.1007/s12289-009-0422-z
In this paper we discuss about the features of a novel numerical method based on the use of separated representations for the variables of interest. This separated representation allows for an easy treatment of problems defined in a space of high number of dimensions, or in which some parameters are…
2009..
Numerical modelling of non-Newtonian flows usually involves the coupling between equations of motion characterized by an elliptic character, and the fluid constitutive equation, which defines an advection problem linked to the fluid history. There are different numerical techniques to treat the hype…
Archives of Computational Methods in Engineering. 2009;16(1):1-30.
DOI : 10.1007/s11831-008-9027-9
Kinetic theory models involving the Fokker-Planck equation can be accurately discretized using a mesh support (Finite Elements, Finite Differences, Finite Volumes, Spectral Techniques, ...). However, these techniques involve a high number of approximation functions. In the finite element framework, …
Journal of Non-Newtonian Fluid Mechanics. 2009;160(2 3):140-156.
DOI : 10.1016/j.jnnfm.2009.03.013
Models encountered in computational physics and engineering, usually involve too many degrees of freedom, too many simulation time-steps, too many iterations (e.g. non-linear models, optimization or inverse identification…), or simply excessive simulation time (for example when simulation in real ti…
Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics. 2009;18(5-6):445-463.
DOI : 10.3166/ejcm.18.445-463
Description of complex materials involves numerous computational challenges. Thus, the analysis of transient models needs for intensive computation. In some of our former works we proposed a technique based on the separated representation of the unknown field able to circumvent the curse of dimensio…
2009..
DOI : 10.1007/s12289-009-0422-z
In this paper we study the problem of compute the solution of a linear system in a separable representation form. It arises in the discretized equations appearing in various physical domains, such as kinetic theory, statistical mechanics, quantum mechanics, and in nanoscience and nanotechnology amon…
2009..
DOI : 10.1007/s12289-009-0435-7
Usual models of colloidal suspensions proceed within the Brownian dynamics (BD) framework. Thus, suspended particles are subjected to different kind of forces coming from the fluid drag, inter-particles potentials, particles-solvent interaction, Brownian forces describing the bombardment that colloi…
2009..
Composites materials reinforced using nano-particles or carbon nano-tubes (CNTs) are more and more used in industry and their modeling is one of the most active research topics in this area. As in usual processes involving composite materials, the main objective is to understand the induced properti…
2009..
DOI : 10.1007/s12289-009-0453-5
This paper reports recent experimental findings and rheological modeling on chemically treated single-walled carbon nanotubes (CNTs) suspended within an epoxy resin. When a CNT suspension was subject to a steady shear flow, it exhibited a shear-thinning characteristic, which was subsequently modeled…
Journal of Rheology. 2009;52(6):1311-1330.
DOI : 10.1122/1.2982932
In this work we analyze the possibilities of applying model reduction in the advanced simulation of materials and processes. The use of such strategies allows impressive computing time savings in the numerical simulations of complex models without degrading the solution accuracy. For this purpose we…
International Journal of Modern Manufacturing Technologies. 2009;1:49-56.
This contribution presents a review of different techniques available for alleviating simulation cost in computational mechanics. The first one is based on a separated representation of the unknown fields; the second one uses a model reduction based on the Karhunen-Loève decomposition within an adap…
International Journal of Material Forming. 2008;1:p.1083-1086.
DOI : 10.1007/s12289-008-0207-9
In the last years, we have assisted to an impressive progression in the numerical modeling capabilities as a result of the progression in computer science but also in the numerical analysis. Thus, new scales have been explored, allowing modeling of richer and finer physical models. In this work we f…
Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics. 2008;17:583-595.
DOI : 10.3166/remn.17.583-595
We propose a rational approach to approximating the various alignment tensors. It preserves the correct symmetry and leads to consistent results. For the case of uniaxial nematic fluids, the decoupling approximation for a tensor of rank $n$ involves $(n−2)/2$ scalar functions $S_n(S_2)$ in terms of …
Journal of Non-Newtonian Fluid Mechanics. 2008;149(1-3):40-55.
DOI : 10.1016/j.jnnfm.2007.05.007
This paper is concerned with the rheological modelling of both chemically treated and untreated carbon nanotube (CNT) suspended in a Newtonian epoxy resin. CNT suspensions generally exhibited shear-thinning characteristic—the apparent viscosity decreases as shear rate increases—when subject to stead…
International Journal of Material Forming. 2008;1(2):83-88.
DOI : 10.1007/s12289-008-0372-x
The fine description of the mechanics and structure of materials at nanometric scale introduces some specific challenges related to the impressive number of degrees of freedom required due to the highly dimensional spaces in which those models are defined. This is the case of quantum mechanics model…
2008;1-17.
DOI : 10.1007/978-3-540-79994-8_1
Nanoscience and nanotechnology as well as the fine modeling of the structure and mechanics of materials from the nanometric to the micrometric scales use descriptions ranging from the quantum to the statistical mechanics. This article revisits the modeling at these scales and points out the main cha…
International Journal for Multiscale Computational Engineering. 2008;6(3):191-213.
DOI : 10.1615/IntJMultCompEng.v6.i3.20
Industrial processes involving composite materials need for efficient numerical simulations in order to optimize the process parameters. Even if the thermo-mechanical models are nowadays well established, efficient simulations need for further developments. In this work we are addressing some of the…
Computer Methods in Applied Mechanics and Engineering. 2008;197(5):400-413.
DOI : 10.1016/j.cma.2007.07.022
Rhéologie. 2008;13:22-30.
Many models in Science and Engineering are defined in spaces (the so-called conformation spaces) of high dimensionality. In kinetic theory, for instance, the micro scale of a fluid evolves in a space whose number of dimensions is much higher than the usual physical space (two or three). Models defin…
2008;1-4.
DOI : 10.1007/s12289-008-0211-0
Many models in Science and Engineering are defined in spaces (the so-called conformation spaces) of high dimensionality. In kinetic theory, for instance, the micro scale of a fluid evolves in a space whose number of dimensions is much higher than the usual physical space (two or three). Models defin…
International Journal of Material Forming. 2008;1:1099-1102.
DOI : 10.1007/s12289-008-0211-0
Nano-science and nano-technology as well as the fine description of the structure and mechanics of materials from the nanometric to the micrometric scales need descriptions ranging from the quantum mechanics to the kinetic theory descriptions characteristic of statistical mechanics. This paper explo…
2008;247-270.
DOI : 10.4203/csets.20.13
Models of kinetic theory provide a coarse-grained description of molecular configurations wherein atomistic processes are ignored. Kinetic theory models can be very complicated mathematical objects sometimes defined in highly multidimensional spaces including the physical space, the time and the con…
2008;1027(1)
DOI : 10.1063/1.2964618
This contribution presents a review of different techniques available for alleviating simulation cost in computational mechanics. The first one is based on a separated representation of the unknown fields; the second one uses a model reduction based on the Karhunen-Loève decomposition within an adap…
2008..
DOI : 10.1007/s12289-008-0207-9
In this work we study the problem of compute the best rank-r approximation to the solution of a class of linear systems. It arises in the discretized equations appearing in various physical domains, such as kinetic theory, statistical mechanics, quantum mechanics,and in nano-science and nanotechnolo…
2008..
jeudi 30 août 2007-8:30 à 9:20-Amphi Esclangon La description fine des matériaux macromoléculaires nécessite de lever un certain nombre de verrous dont plusieurs sont à caractère numérique. Pour s'affranchir de telles descriptions il faudrait sans doute mettre en place des modélisations multi-échell…
2007..
Cette étude concerne des simulations numériques stationnaires, non-isothermes, par volumes finis dans des situations 2D et 3D de contractions brusques, pour des fluides incompressibles anélastiques (newtonien, Carreau-Yasuda) et viscoélastiques (modèles différentiels de Phan-Thien/Tanner (PTT)), ave…
2007..
Kinetic theory models described within the Fokker–Planck formalism involve high-dimensional spaces (including physical and conformation spaces and time). One appealing strategy for treating this kind of problems lies in the use of separated representations and tensor product approximations basis. Th…
Journal of Non-Newtonian Fluid Mechanics. 2007;144(2-3):98-121.
DOI : 10.1016/j.jnnfm.2007.03.009
Dans les dernières années nous avons pu assister à une progression sans précédent des performances de la simulation numérique suite à la croissance de la puissance informatique et au développement des méthodes numériques. De nouvelles échelles ont pu être analysées, permettant une modélisation fine …
2007..
Description of macromolecular materials involves numerous computational challenges. Accurate descriptions of such materials need for a multiscale description and the definition of pertinent bridges between the different scales. The finest description starts at the atomic level where quantum mechanic…
2007..
Kinetic theory models involving the Fokker–Planck equation are usually solved in the framework of stochastic approaches, which allows us to circumvent the difficulties related to the multidimensional character of that equation. In fact, the Fokker–Planck equation governs the evolution of the distrib…
Modelling and Simulation in Materials Science and Engineering. 2007;15:639-652.
DOI : 10.1088/0965-0393/15/6/004
La mise en forme d'un plastique renforcé par des fibres courtes nécessite l'écoulement d'un fluide viscoélastique contenant une suspension de fibres. La modélisation de ce type d'écoulement fait intervenir des couplages entre la viscoélasticité, les fibres et la cinématique. La microstructure du mil…
2007..
International Journal of Forming Processes. 2007;10(4):447-470.
Models of kinetic theory provide a coarse-grained description of molecular configurations wherein atomistic processes are ignored. The Fokker-Planck equation related to the kinetic theory descriptions must be solved for the distribution function in both physical and configuration spaces. When the mo…
Applied Rheology. 2007;17/2(26494):1-14.
DOI : 10.3933/ApplRheol-17-26494
This work focuses on the resolution of the Fokker-Planck equation that governs the evolution of the fibers orientation distribution. To reduce the computing time, that equation is solved along some flow trajectories in order to extract the significant information of the solution from the application…
International Journal of Forming Processes. 2007;10/3:361-385.
DOI : 10.3166/ijfp.10.361-385
This work focuses on the solution of thermal models usually encountered in composite plates welding processes that involve a certain number of numerical difficulties related to: (i) the very fine mesh required due to the small domain thickness with respect to the other characteristic dimensions as w…
2007;1-4.
DOI : 10.1063/1.2740826
Le but essentiel de ce travail est de donner une contribution à la simulation des comportements microscopiques de la reptation des polymères fondus en réduisant le coût de calcul. Dans ce cadre nous proposons deux modèles de reptation : le modèle de Doi-Edwards avec hypothèse d'alignement indépendan…
2007;1-4.
Models encountered in chemical engineering usually involve a large number of degrees of freedom related to its multidimensional and multiphysical character. Model reduction is an appealing alternative for treating efficiently (fastly and accurately) such models. In this work we will illustrate some …
World Journal of Chemical Engineering. 2007;1(1):3-12.
Kinetic theory models involving the Fokker–Planck equation can be accurately discretized using a mesh support (finite elements, finite differences, finite volumes, spectral techniques, etc.). However, these techniques involve a high number of approximation functions. In the finite element framework,…
Journal of Non-Newtonian Fluid Mechanics. 2006;139(3):153-176.
DOI : 10.1016/j.jnnfm.2006.07.007
The present study addresses the issue of the steady regime assumption in flows involving short fibers usually introduced for the analysis of rheometric flows or in the simulation of some kind of forming processes as is the case of the extrusion. For this purpose we analyze the solution of the Fokker…
International Journal of Forming Processes. 2006;9(4):431-456.
La modélisation numérique d’un écoulement de suspensions de fibres courtes nécessite une description de l’évolution microstructurelle. Pour décrire cet état microstructurel, il est possible d’utiliser la densité de probabilité d’orientation des fibres dont l’évolution est gouvernée par l’équation de…
2006..
Kinetic theory models of complex fluids involve the resolution of the advectiondiffusion Fokker-Planck equation that is usually performed using stochastic approaches. Stochastic simulation for Finitely Extensible Non Elastic (FENE) dumbbells has been successfully applied (Keunings 1997; Keunings 200…
Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics. 2006;15(5):481-494.
DOI : 10.3166/remn.15.481-494
The numerical modeling of forming processes requires powerful numerical tools able to describe the multi-physics and multi-scale encountered, the large 3D transformations, ... but also the mechanical descriptions of material and process. Many difficulties have been identified, all of them being the …
2006..
Karhunen-Loève expansion and snapshot POD are based on principal component analysis of series of data. They provide basis vectors of the subspace spanned by the data. All the data must be taken into account to find the basis vectors. These methods are not convenient for any improvement of the basis …
Archives of Computational Methods in Engineering. 2006;13(1):91-128.
DOI : 10.1007/BF02905932
Stochastic simulation for finitely extensible non-linear elastic (FENE) dumbbells has been successfully applied (see the review paper of Keunings [R. Keunings, Micro–macro methods for the multiscale simulation viscoelastic flow using molecular models of kinetic theory, in: D.M. Binding, K. Walters (…
Journal of Non-Newtonian Fluid Mechanics. 2006;134(1-3):136-147.
DOI : 10.1016/j.jnnfm.2006.01.007
In this work, the model of Doi-Edwards with independant alignment approximation describing the dynamics of polymer melts is simulated. The main aim of this work is the analysis of some new simulation techniques operating on the Fokker-Planck equation related to that model. For this purpose we consid…
2006..
DOI : 10.1115/FEDSM2006-98057
Liquid crystalline polymers (LCPs) are macromolecules that contain long, rigid or approximately rigid segments. Because of these rigid units, LCPs can display structural phase transitions between isotropic (disordered) and nematic (oriented) states. LCPs are classified as thermotropic or lyotropic d…
2006..
Kinetic theory models involving the Fokker-Planck equation, can be accurately discretised using a mesh support (Finite Elements, Finite Differences, Finite Volumes, Spectral Techniques). However these techniques involve a high number of approximation functions. When the model involves high dimension…
2006;193-215.
Numerical modeling of non-Newtonian flows typically involves the coupling between the equations of motion characterized by an elliptic character, and the fluid constitutive equation, which is an advection equation linked to the fluid history. In this work we propose a coupling between the natural el…
Revue Européenne des Éléments Finis. 2005;14(6-7):903-923.
DOI : 10.3166/reef.14.903-923
Les suspensions de fibres courtes sont abondamment impliquées dans l'industrie des matériaux composites. La connaissance de la microstructure finale des pièces est essentielle pour la prédiction des propriétés mécaniques. De même, la prédiction d'une telle microstructure pourra aussi servir à l'opti…
Revue des composites et des matériaux avancés = Journal of Composite and Advanced Materials. 2005;15:323-337.
DOI : 10.3166/rcma.15.323-337
Kinetic theory models of complex fluids involve the resolution of the advection- diffusion Fokker-Planck equation that is usually performed using stochastic approaches. Stochastic simulation for Finitely Extensible Non Elastic (FENE) dumbbells has been successfully applied (Keunings 1997; Keunings 2…
2005..
DOI : 10.3166/remn.15.481-494
KarhunenLò eve expansion and snapshot POD are based on principal component analysis of series of data. They provide basis vectors of the subspace spanned by the data. All the data must be taken into account to find the basis vectors. These methods are not convenient for any improvement of the basis …
2005;43
DOI : 10.1007/BF02905932
In this work we present a new numerical strategy to treat the 3D Fokker-Planck equation in steady recirculating flows. This strategy combines some ideas of the method of particles, with a more original treatment of the periodicity condition, which characterizes the steady solution of the Fokker-Plan…
Rheologica Acta. 2005;44:406-417.
DOI : 10.1007/s00397-004-0422-3
In this work we have analyzed the application of a deterministic approximation of the diffusion term in the Fokker-Planck equation using smooth particles for computing its steady solution in a steady recirculating flow. The main idea of this approach lies in the introduction of the Fokker-Planck dif…
2005;43:1-15.
DOI : 10.1007/3-540-27099-X_1
In this work we have analyzed the application of a deterministic approximation of the diffusion term in the Fokker-Planck equation using smooth particles for computing its steady solution in a steady recirculating flow. The main idea of this approach lies in the introduction of the Fokker-Planck dif…
2003..
DOI : 10.1007/3-540-27099-X_1
The crystallization of thermo-plastic polymers under strain is considered both theoretically and experimentally. The thermo-mechanical model presented here is performed in the framework of the so-called generalized standard materials. In our model we couple in a very natural way the kinetics of crys…
Computer Methods in Applied Mechanics and Engineering. 2003;192(28 30):3245-3265.
DOI : 10.1016/S0045-7825(03)00349-9
Nous présentons dans ce travail un modèle de cristallisation, d'un polymère viscoélastique, induite par son écoulement. Dans un travail antérieur [A. Poitou, A. Ammar, Polymer crystallization induced by strain or flow : a thermodynamic approach, C. R. Acad. Sci. Mécanique (Janvier 2001) 5–11], nous …
Mechanics & Industry. 2002;3(6):525-535.
DOI : 10.1016/S1296-2139(02)01198-3
We present in this paper a thermodynamic model for flow induced crystallization of a thermoplastic. The thermomechanical framework (generalized standard materials) allows us to couple in a very natural way the kinetics of crystallization with the mechanical history experienced by the thermoplastic[1…
Macromolecular Symposia. 2002;185(1):243-255.
DOI : 10.1002/1521-3900(200208)185:1<243::AID-MASY243>3.0.CO;2-S
Dans le but de simuler l’extrusion de polymères, nous utilisons le modèle pom-pom pour décrire le comportement en écoulement. Ce modèle décrit l’état du polymère avec deux variables moléculaires : l’étirement et l’orientation des chaînes. Nous proposons une partition des déformations élastiques et v…
Rhéologie. 2002;1:1-10.
We address in this paper the problem of blow molding for a polymer exhibiting a deformation induced crystallization (e.g. Poly EthyleneTerephthalate or PET). In a first part, we give the equations of a model that couples the mechanics to the crystallization for a class of molecular models (e.g. Maxw…
International Journal of Forming Processing. 2002;5(2-3-4):401-413.
DOI : 10.3166/ijfp.5.413-421