ABSTRACT
Most practical problems involve complex geometries. To get a better description of an irregular boundary, it is possible to let the wall boundary intersect the regular coordinate lines at irregular locations, giving irregular shapes and sizes of boundary cells. These cells need special discretisation and can introduce considerable errors into the implementation of a boundary condition. In body-fitted coordinate transformation for mapping complex geometries into regular shapes, the computational mesh is always made rectangular by suitable transformations. However, the process of mapping from Cartesian coordinates to body-fitting curvilinear coordinates is very cumbersome. Often there are difficulties in controlling the grid size and grid skewness. The need for greater flexibility in the flow simulation for complex geometries has led to the development of solution algorithms based on non-orthogonal meshes. Chapter 7 is devoted to the application of the finite volume method in complex geometries, highlighting the advantages of using a non-orthogonal co-located grid. The detailed discretisation procedures for non-orthogonal structured grids, Cartesian structured grids and unstructured grids with co-located meshes are described, as is the implementation of the SIMPLE algorithm for these cases.
