CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Low Turbulence Intensity Simulation

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

LinkBack Thread Tools Display Modes
Old   October 26, 1999, 15:35
Default Low Turbulence Intensity Simulation
J. McCarthur
Posts: n/a

I am trying to simulate the 3D turbulent flow field inside a turbine rotor using R-K and k-epsiln/ARSM turbulence model. I have got good results when the inlet turbulence intensities are 15% and 11%, respectively. But when I try 1% inlet turbuelence intensity, the calculation does not converge, nor diverge. The error just stays a much higher level than the 15% Tu case.

Does anybody know why it is and how to improve this? Thanks a lot.

  Reply With Quote

Old   October 26, 1999, 16:17
Default Re: Low Turbulence Intensity Simulation
Jonas Larsson
Posts: n/a
Using an explicit Runge-Kutta solver to solve k-epsilon becomes more and more difficult the lower the turbulence level is. When you come down to 1% or even lower you often have to take special care to obtain convergence. You can spend years trying to fix this problem (I did), but in the long run I think that you'll be better of switching to an implicit method, at least for k and epsilon. 1% is not impossible though. I don't know what kind of "tricks", "limiters" and "stability enhancements" you have in your code today, but there are many things that you can do which will reduce the problems.

Btw, I'm not sure what you mean with that the error stays high - what error? Do you mean residuals?
  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
Natural convection - Inlet boundary condition max91 CFX 1 July 29, 2008 20:28
Turbulence intensity scale Mirek FLUENT 1 May 26, 2004 08:27
turbulence intensity co2 FLUENT 2 December 27, 2003 19:41
Taylors+hypothesis related to turbulence intensity ashishraval Main CFD Forum 0 November 19, 2003 06:22
Turbulence Intensity Vs CFD Simulation Apple L S Chan Main CFD Forum 3 December 15, 1998 18:28

All times are GMT -4. The time now is 01:32.