Capture d'interface et application au procédé d'injection assistée eau

http://hdl.handle.net/2042/16392International audienceNous proposons une amélioration des techniques de capture d'interfaces, pour la simulation d'écoulements multiphasiques, en utilisant une méthode de h-adaptation de maillage. Une technique d'adaptation de maillage anisotrope basée sur les variations de gradients de la fonction level-set permet de capturer les discontinuités des paramètres physiques qui caractérisent les écoulements fortement hétérogènes. Cette méthode permet l'observation précise de l'évolution des différentes phases (eau/ polymère liquide eau/ polymère solide) ainsi que leurs interactions. Une application directe de cette amélioration est la simulation des problèmes multiphasiques complexes intervenant dans le procédé de fabrication de pièces creuses tel que l'injection assistée eau = We propose an improvement of interface capturing techniques by using an h-adaptation technique to improve computation of the multiphase flows. An anisotropic mesh adaptation technique based on variations of the level-set function allows a better capture of the discontinuities of the physical parameters that characterize the strongly heterogeneous flows. This method allows an accurate observation of the evolution of the various phases (water/liquid polymer, water solid polymer) as well as their interactions. A direct application of this improvement is the simulation of complex multiphase problems involved in the manufacturing processes of hollow parts such as the water assisted injection process

Multifluid Flows, Interface Capturing and Application to the Simulation of the Water Assisted Injection Molding Process

International audienceIn this paper, we present a 3D finite element approach to compute multifluid flows. Special attention is given to capture the water/polymer interface, that can be obtained used a VOF (Volume of Fluid) or a Level Set technique, with or without adaptative meshing. Results are shown, in for 2D and 3D parts

Two-phase model of liquid-liquid interactions with interface capturing: Application to water assisted injection molding

Reprinted with permission from AIP Conf. Proc.May 17, 2007 -- Volume 908, pp. 361-368 MATERIALS PROCESSING AND DESIGN; Modeling, Simulation and Applications; NUMIFORM '07; Proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes; doi:10.1063/1.2740838. Copyright 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of PhysicsInternational audienceIn this paper, a two phase model to compute liquid-liquid flows is presented. We consider that one phase is a highly viscous thermodependent liquid (polymer phase), whereas the second one is a low viscosity low temperature fluid (water). The first part of this paper concerns capture of the interface between the water and the polymer (or determination of the phase field function). Classical VOF and Level set techniques have been implemented and were ameliorated using mesh adaptation techniques. To accurately determine the velocity field, a two-phase formulation is considered, based in the theory of mixtures, and we introduce a scalar parameter, the phase fraction quantifying the presence of each phase in each point of the computational domain. A friction type coupling between both phases is retained. Using the mixed finite element method within an eulerian framework, we calculate in a single system the whole kinematic variables for both liquids (velocity and pressure of each phase). Results are shown, for 2D and 3D part

Adaptive anisotropic mesh and interface capturing problem

This talk will focus on some of the recent progresses in anisotropic mesh adaptation in finite element calculation. The main purpose of anisotropic meshing is to enable high stretched elements in the directional features of the searched solution. For particular simulation problem, we show a spectacular gain in accuracy while controlling the amount of calculation. We explain how anisotropic meshers are driven by a continuous metric field to measure length in a Riemannian way. Following the interpolation error estimation theory, the metric field must be related to the second derivative of representative field associated with the discrete solution. Afterwards, the anisotropic a posteriori error estimator drives the search of the optimal mesh (metric) that minimizes the error estimator under the constraint of a given number of nodes. We will show the necessary tools require achieving parallel anisotropic mesh adaptation: the metric construction and global objective function, the serial mesh generator (MTC) in a parallel context, the repartitioning the mesh after each re-meshing stage. Numerical 2D and 3D applications are presented here to show that the proposed anisotropic error estimator gives an accurate representation of the exact error. We will show also, that the optimal adaptive mesh procedure provides a mesh refinement and element stretching which appropriately captures interfaces for practical application problems that are unreachable by simply refining the meshes

Adaptive mesh refinement for the numerical modelling of complex microstructural evolution applications

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Dynamic parallel adaption for three dimensional unstructured meshes: Application to interface tracking

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