Dear all, I am working with rotating flows. First I used the "simple" discretization scheme and run the model for around 1500 iterations. For momentum, I used First order. It went smoothly. When I changed it to the second order for momentum and Presto for PRessure, after around 1800 iterations, the solution started to diverge. Also I tried with the multiple reference frame. I could avoid the divergence till some more iterations but that as well started to diverge. CAn anybosy help me in this regard? Thanks

try using other schemes like body force wieghted under pressure is always good for rotating flows.

This site says:

http://www.fluentusers.com/defreq/ne...Conditions.htm

FLUENT Defects ID: 12318

Summary: PRESTO scheme for pressure interpolation when used in some cases with the FIX option for velocity can cause divergence.

Product Name: Fluent6 Component Name: Boundary Conditions Version Found: 6.0.13 Version Fixed: 6.0.13 Reported date: 11/16/01 11:53:26 AM

Description: The FIX option with PRESTO interpolation scheme leads to the divergence of the case. files are in the appropriate folder. boite_standard.cas.gz boite_standard.dat.gz --> convergence with standard interpolation scheme. boite_bfw.cas.gz boite_bfw.dat.gz --> convergence with body force weighted interpolation scheme. boite_PRESTO.cas.gz boite_PRESTO.dat.gz --> divergence with PRESTO interpolation scheme. source.c --> udf who impose the definition of the fix velocity.