CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   convergence in different boundary condition (http://www.cfd-online.com/Forums/cfx/20613-convergence-different-boundary-condition.html)

joseph September 1, 2004 02:01

convergence in different boundary condition
 
hello all

I have a problem with bad convergence. This model was well solved. But i changed the outlet mass flow rate, the model's convergence was bad. So i adjusted the physical timescale, still the residual is not satisfactory. Can somebody help me?. if you need more explaination, please e-mail me.

thanks in advance.


HK September 1, 2004 02:51

Re: convergence in different boundary condition
 
Try few of these:

1)solve for laminar flow, then use the solution as a start for turbulent cases.

2)start with a very small timescale and then during the iteration, increase the time scale

3)can you use 'openning' BC?

HK

KKA September 2, 2004 13:04

Re: convergence in different boundary condition
 
In addition to what HK said, you might

1.check that the mass is balanced. That correct mass flow is being specified at the outlet.

2.check different scheme too, thus either UPWIND or Blend and can then be changed to higher scheme!!

Regards


All times are GMT -4. The time now is 12:35.