when simulated the three way catalyst of engine exhaust ,the catalyst was treated as porosity,so the alpha and beta were defined. the alpha is 2.5 and beta is 2450 in the flow dircetion, the other alpha and beta were definded as 1.e+07 .the result of total pressue is very strange, it exceeds 1.0+06 Pa .the total pressure is reasonable when starcd 3.24 was used to calculate the catalyst system with same boundary condtions, the total pressure is about 2.2 bar. could you give me some suggestion?

I was told porous medium was not on the list of models upgraded into star-cd v4. From 3.26 a small selection of models was selected to be ready for 4.02, then further previous models added and tested for 4.04, etc...to 4.06. I think porous medium is developed for STAR-CCM+ because there is surface chemistry with it. But it is not on the list for star v4. Ask your local support I guess.

Porous media has been supported from v4.00. There we issues with tet. meshes within such regions, but this is evidently fixed now - all in the release notes.

Also regarding features in v4, my opinion is the reverse - ie most feature WERE in v4.0, but a few were missing, and have been progressively added (mainly engine combustion related) and v4.06 and v4.08 mean all users can convert from v3.26.

BTW to fix your problem: try a test reducing a & b in the other directions one or two orders of magnitude. Cell quality in there - try cell remediation, URF etc.

"ie most feature WERE in v4.0". This is incorrect. Only basic models were initially tested for 4.0 and then the additional tests for further modelling option occurred later: 4.02, 4.04, 4.06, etc... on a step by step basis.