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-   -   Non Convergence of 3D Heat transfer cfd problem (http://www.cfd-online.com/Forums/main/8427-non-convergence-3d-heat-transfer-cfd-problem.html)

Balraj December 8, 2004 13:04

Non Convergence of 3D Heat transfer cfd problem
 
I am trying to perform cfd analysis on 3D rectangular cavity problem with a hot and cold opposite sides with a temp difference of 10 deg and the other 2 sides being adiabatic.

I did a couple of runs with the following parameters:

1) Aspect ratio - 25:1 (H/L), Secondary Aspect ratio - 1:2 (W/L), Ra = 92,625, vertical (90deg) and horizontal orientation(0deg) of the cavity. I was able to achieve convergence in both the cases

2) I changed the secondary aspect ratio to 5:1 and did the run again. This time around i could not achieve convergence for 0deg orientation.

I am using fluent to perform the analysis. I cannot describe the entire simulation parameters here. But if someone could let me know, by their experience, the parameters I can target to achieve convergence. I am trying to get constant flux on the heat and cold sides for over atleast 100 iterations.

I would appreciate your help in this regard.

Joe Brian December 9, 2004 01:03

Re: Non Convergence of 3D Heat transfer cfd proble
 
Sounds you are facing quite a classical problem. You may want to look for papers already published. I am not sure what the number is. Ra or Gr??? You will be able to find the result with the same non-dimensionalized number from the papers.

Or from my past experience, the flow may not be steady but transient or there my be some bifurcations.

Good luck!!

-Joe

Joe Brian December 9, 2004 01:19

Re: Non Convergence of 3D Heat transfer cfd proble
 
Forgot to mention. CFX was one of the three got into consideration.

-Joe

Joe Brian December 9, 2004 01:24

Re: Non Convergence of 3D Heat transfer cfd proble
 
Sorry!

This shouldn't be here. Should be under Re: FLUENT/CFX/STARCD as CFD modelers -

I've been too busy posting messages.

-Joe


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