I want to know how I can model complex geometry in CFD.If anybody knows please guide me.

Thank you, Mehdi

use a tet mesher?

thank you , but what's the Tet mesher and also I wrote a code for radiation in cylindrical and cartesian coordinate and I want to develop it for any geometry.I heard something about body fited coordiante but I don't know about it.

My thoughts are that body fitted coordinates are not really for complex geometries. For complex geometries you have few options: Create a number of blocks with hex meshes (takes a long time) Rewrite your code for a cartesian mesh Use a hex mesher

Body-fitted coordinates are ordered (structured) grid points that follow the body surface, and mathematically are mapped from a rectangular (j,k,l) space to the physical space via the transformation metrics. Most any good CFD book will have a section on this, and Hoffman's entry-level CFD book does a particularly good job of describing body-fitted coordinates, as well as rudimentary grid generation techniques.

The problem you will run into with complex geometries is that it is usually not possible to grid the entire volume with one structured, body-fitted grid. Thus, you have to resort to block-structured grids, where smaller patches are gridded and the grids meet at block interfaces with special boundary conditions to handle information passing, or using overset grids, which involve grids that overlap and require some interpolation technique to transfer information across boundaries.