dartmouth讲稿-CFD网格的划分.pdf

Lecture 7 - Meshing Applied Computational Fluid Dynamics Instructor: André Bakker © André Bakker (2002-2006) 1 © Fluent Inc. (2002) Outline • Why is a grid needed? • Element types. • Grid types. • Grid design guidelines. • Geometry. • Solution adaption. • Grid import. 2 Why is a grid needed? • The grid: – Designates the cells or elements on which the flow is solved. – Is a discrete representation of the geometry of the problem. – Has cells grouped into boundary zones where b.c.’s are applied. • The grid has a significant impact on: – Rate of convergence (or even lack of convergence). – Solution accuracy. – CPU time required. • Importance of mesh quality for good solutions. – Grid density. – Adjacent cell length/volume ratios. – Skewness. – Tet vs. hex. – Boundary layer mesh. – Mesh refinement through adaption. 3 Geometry • The starting point for all problems is a “geometry.” • The geometry describes the shape of the problem to be analyzed. • Can consist of volumes, faces (surfaces), edges (curves) and vertices (points). Geometry can be very simple... … or more complex geometry for a “cube” 4 Geometry creation • Geometries can be created top-down or bottom-up. • Top-down refers to an approach where the computational domain is created by performing logical operations on primitive shapes such as cylinders, bricks, and spheres. • Bottom-up refers to an approach wher