International audienceThe anisotropic mesh adaption techniques in the last decade have dramatically improved the numerical simulations accuracy of complex problems. An optimal anisotropic mesh adaption consists in refining and coarsening the mesh, by using a metric to specify stretching directions, in order to accurately capture physical anisotropy such as shock waves, contact discontinuities, vortexes, boundary layers and free surfaces. Thus, we propose in this paper, an anisotropic a posteriori error estimator that controls the error due to mesh discretization in all space directions. From the a posteriori error analysis, we obtain an optimal metric (optimal mesh) as a minimum of an error indicator function and for a given number of elements. The optimal metric obtained is used to build an optimal mesh for the given number of elements. Furthermore, solutions for the physical problems illustrated here are often more accurate on adapted meshes than those obtained on globally-refined meshes and at a much lower cost

Abstract. In 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 parts.