Hello guys

Which software for preprocssing is best.

p.s while importing IGS file in gridgen it gives error saying segmentation voilation. on the other hand same geometry is easily imported in gambit. any suggestion

It's always a mystery with IGES. Every package writes IGES differently - and every reader has different benefits. Go with the meshing rather than the geometry reader - as Tech Support will generally make the reading work.... ICEM seems the most powerful/flexible - but then also can be complicated to use.

Save yourself alot of pain and bother and avoid doing geometry transfers via IGES. Use the direct CAD importer for whichever grid generator you choose to use.

I use ICEMCFD which I find to be a very capable product (except that its ability to inflate prism layers on mixed hex/tet grids is pathetic).

I find gridgen's UI quite horrid. An awefull 1970's throwback.

I would go for ICEM or ANSA. Gridgens volume meshing procedure is pretty slow and gives a lot of bad cells. I used Gridgen only for surface meshing, and created the prisms/tets in Tgrid.

I haven't tried Gambit, so no comments for that one.

Gridgen is not too bad in the sense that it's pretty flexible, and once you understand how the software work, it should be pretty quick for meshing. However, making the block for hexa mesh is very time consuming for Gridgen. I tried only for a year, before ICEMCFD is available to CFX user. Not sure about the recent improvement in Gridgen (after V15.02).

ICEM is powerful, but still has lots of bugs in the program, even for the latest version. You've to continously download the service pack to fix the problem anyway. Blocking is really easy in ICEM, and it has automatic O block generator, which I find it very useful for my application.

I am using the software callled cfdesign which has automatic mesh generator. It meshes vey complx geometries also. It has very good meshing speed also.