CFD Online Logo CFD Online URL
Home > Forums > CFX

max residuals near max turbulence intermittency

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   June 3, 2008, 22:35
Default max residuals near max turbulence intermittency
Posts: n/a
Hello everyone,

I am simulating the flow in a diffuser with SST transitional model in transient mode. The boundary layer parameters are y+<1 and expansion 1.1. The timestep is 0.0001s. The inlet velocity is about 20m/s. The flow is with both laminar and turbulence separation.

I monitor the pressure, turbulence energy and velocity in three points of freestream, laminar and turbulence separation region. The attachment is some results. We can observe developing oscillation in these pictures, which I think non-physical.!5B651E09CD31334B!131/

Then I adopt double precision solver, decrease and increase the timestep, however the problem remains. Fortunately when I switch second order backward euler to first order, the developing oscillation begins to be weaker.

I also check the residual distribution(P-mass, u-mom...) and find that maximum residuals are usually located near the maximum turbulence intermittency.

How can I solve the problem besides by switching to first order backward euler?

Thank you!


  Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Force can not converge colopolo CFX 13 October 4, 2011 22:03
Discussion: Reason of Turbulence!! Wen Long Main CFD Forum 3 May 15, 2009 09:52
On the damBreak4phaseFine cases paean OpenFOAM Running, Solving & CFD 0 November 14, 2008 22:14
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 19:07

All times are GMT -4. The time now is 12:28.