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-   -   LES simulations (http://www.cfd-online.com/Forums/fluent/35060-les-simulations.html)

Ben Andrus November 12, 2004 15:41

LES simulations
 
I am having a problem getting accurate results from an external flow simulation I am running with the LES turbulence model. The velocity plots appear to be reasonable however the pressure is very stange. It is low at the inlet and steadily climbs towards the outlet to the operating pressure. On a contour plot it appears as stripes parallel to the inlet increasing in pressure as they get closer to the outlet. Any ideas on what might cause this? I have tried lowering my time step but it still appears in the solution. Does it have anything to do with the reference pressure location?

Ben

Chetan Kadakia November 12, 2004 20:47

Re: LES simulations
 
What are you running flow over? How far is the outlet from the object (compared to the size of the object). Why are you using LES? Many more questions can be asked... Give more info so we can help.

zxaar November 22, 2004 06:03

Re: LES simulations
 
check boundary conditions, with pressure inlet if things are not specified properly u get this kinda result

Helper December 4, 2004 10:23

Re: LES simulations
 
Chance is that you're unknowingly using the random number generator with a very high turbulence intensity (or its equivalents) at your velocity inlet. Try zero turbulence intensity. Don't feel too bad that you have to do this, since random number is a poor representation of turbulence anyway. Better inlet stochastic velocity BCs are on the way.


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