Toward an improved wall treatment for multiple-correction k-exact schemes

Improved wall boundary treatments are investigated for a family of high-order Godunovtype finite volume schemes based on k-exact polynomial reconstructions in each cell of the primitive variables, via a successive corrections procedure. We focus more particularly on the 1-exact and 2-exact schemes which offer a good trade-off between accuracy and computational efficiency. In both cases, the reconstruction stencil needs to be extended to the boundaries. Additionally, information about wall curvature has to be taken into account, which is done by using a surface model based on bicubic Bézier patches for the walls. The performance of the proposed models is presented for two compressible cases, namely the inviscid flow past a Gaussian bump and the viscous axisymmetric Couette flow

P2 mesh optimization operators

International audienceCurved mesh generation starting from a P1 mesh relies on mesh deformation and mesh optimization techniques. Mesh optimization techniques consist in locally modifying the mesh in order to improve it with respect to a given quality criterion. This work presents the generalization of two mesh quality-based optimization operators to P2 meshes. The generalized operators consist in mesh smoothing and generalized swapping. With the use of these operators, P2 mesh generation starting from a P1 mesh is more robust and P2 connectivity-change moving mesh methods for large displacements are now possible

Mesh generation - Applications and adaptation

link_to_subscribed_fulltex

Fast Delaunay triangulation in three dimensions

An efficient algorithm for Delaunay triangulation of a given set of points in three dimensions based on the point insertion technique is presented. Various steps of the triangulation algorithm are reviewed and many acceleration procedures are devised to speed up the triangulation process. New features include the search of a neighbouring point by the layering scheme, locating the containing tetrahedron by random walk, formulas of important geometrical quantities of a new tetrahedron based on those of an existing one, a novel approach in establishing the adjacency relationship, the use of adjacency table and the management of memory. The resulting scheme is one of the fastest triangulation algorithms known to the authors, which is able to generate tetrahedra generation rate of 15 000 tetrahedra per second for randomly generated points on a HP 735 machine. © 1995.link_to_subscribed_fulltex

3D Hybrid Mesh Generation For Reservoir Flow Simulation

A great challenge for flow simulators of new generation is to gain more accuracy at well proximity within complex geological structures. For this purpose, a new approach based on hybrid mesh modeling was proposed in 2D in [1]. In this hybrid mesh, the reservoir is described by a structured quadrilateral mesh and drainage areas around wells are represented by radial circular meshes. In order to generate a global conforming mesh, unstructured transition meshes constituted by convex polygonal elements satisfying finite volume properties are used to connect together these two structured meshes. Thus, the resulting mesh allows us to take full advantages of simplicity and practical aspects of structured meshes while complexity inherent to unstructured meshes is introduced only where strictly needed

Adaptive remeshing for industrial unsteady CFD

FLUSEPA is an advanced simulation tool which performs a large panel of aerodynamicstudies. It is the unstructured finite-volume solver developed by Airbus Defence& Space tocalculate compressible, multidimensional, unsteady, viscous and reactive flows around bodies in relative motion. The numerical strategy in FLUSEPA is designed for highly compressible flow and keeps its accuracy regardlessof the grid. According the desired accuracy, a second-order accurate shock-capturing scheme is generally used for RANS and URANS simulations and a fourth order accurate vortex-centredscheme is used for hybrid RANS/LES simulations[1].In this paper we introducean adaptive meshing approach to accurately represent unsteady flows in FLUSEPA.The meshing strategy is based on amulti-overlapping grid intersection which is conservative and allows to quickly and properly mesh 3D complex geometries. It can be seen as a CHIMERA strategy without interpolation. Each part of the bodiesis meshed independently and immersed in background grids.This technique will be largely described for it differs from the commonly used interpolation-based CHIMERA methods.The adaptive mesh construction is based on a simple 2-1 balanced octree approach. Different criteria for refinement will be tested:one relying on the Ducros[2]sensor, another is a basic hessian and the last one is based on the resolved kinetic energy. The aim of this study is to obtain a versatile module for industrial applications combining different criteria. The test case is a transonic turbulent flow around a square cylinder at a Mach number of 0.9 and Reynolds number of 4.105based on the experimental conditions of Nakagawa[3]. Computations are carried out using a CFL of 0.8 and on a Cartesian grid.The study will be focused on theinteraction between the von Karman eddy street and theshock wave