PISO vs. SIMPLE

benedikt flurl

Im testing at the moment my new implemented PISO routine, and I can not find any advantages compared with SIMPLE. I am testing with the Karman Vortex Street. In PISO and in SIMPLE it is no Problem to set the underrelaxation factors for pressure correction to 1 (underrelaxation for u,v 0.5). And SIMPLE converges as rapidly as PISO. Has anybody from you good experience with the PISO algorithm and can anybody tell me, when I can justify running PISO without iteration (for this reason it was developed I think?!). Thank you very much for your help!

Benedikt.

PS: Is the Karman Vortex street a bad testcase for comparing PISO with SIMPLE? PPS: I can let run PISO and SIMPLE without iterations an get not bad results (compared with eperimental data)