Anisotropic Mesh Adaptation Through Edge Primitive Operations

Abstract

The development of a modular library for anisotropic adaptation of tetrahedral unstructured meshes is presented. The adaptive method relies on repeated application of simple edge break and collapse operations to modify a mesh such that individual edge lengths match a given anisotropic metric tensor field. The procedure maintains a continuous metric distribution through consistent interpolation of the initial metric field. Several methods are integrated within the library to preprocess the initial metric field so as to limit minimum and maximum local mesh sizes, control stretching rates of mesh size and/or anisotropy, and ensure smoothness of the resulting metric distribution. In addition, procedures to limit the metric distribution relative to the initial mesh and/or to the local geometry surface curvature are presented. Finally a linear-elastic mesh deformation method coupled with application provided geometric call-back functions is used to deform the adapted mesh to the geometry surface. The modular library implementation simplifies integration of the adaptive capability with new flow solver and mesh generation packages. Examples from multiple flow solvers and a mesh manipulation tool are presented.

Unstructured Grid Adaptation: Status, Potential Impacts, and Recommended Investments Towards CFD 2030

“…Many variants of local operator adaptive mechanics are currently employed. [37][38][39][40][41][42][43][44] This has been shown to be unified by the cavity operator, 45 which has yet to be widely implemented but shows promise for producing semi-structured metric-orthogonal regions in the boundary and interior of the domain. 46,47 The di↵erences between a mapped isotropic method and a metric-orthogonal method are shown in Fig.…”

CFL3D, FUN3D, and NSU3D Contributions to the Fifth Drag Prediction Workshop

“…The tetrahedral elements are adapted with a general metric-based edge primitive scheme. 57,58 Work is ongoing to improve the parallelization of this edge primitive scheme. However, in its current form, the partition boundaries are not evenly adapted.…”

Serial and Parallel Mesh Modification Through a Unique Cavity-Based Primitive

“…In comparison with adaptive algorithms of [23,24,28], we define new operators to be used instead of classical edge-based operators. The main interests are (i) the removal of any ad'hoc quality tolerances as in [23], (ii) faster convergence of the process as the size cavity is adapted to favor the operation, (iii) better anisotropy as during a (re)insertion, the lengths are controlled in every directions.…”

“…According to a given metric tensor field, the mesh is modified iteratively to generate an almost unit mesh, i.e., where all edges have a length given by (2) close to one. Following previous works on anisotropic mesh generation [23,28], an edge is said to be unit when its length is in the range […”