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-   -   Which AMG Linear Solver (http://www.cfd-online.com/Forums/star-ccm/86001-amg-linear-solver.html)

 Zuixy March 11, 2011 10:42

Which AMG Linear Solver

Hey,

I have a problem with solid body and a fluid flow. I use a segregated Solid Energy Model for the solid body. My Problem is that the temperatur changes just very very slowly. There a no big temperature changes due to the fluid. Any suggestions how i can improve the solver?

Thx

 alastormoody11 March 14, 2011 03:41

hi,

the AMG linear solver just solves the simultaneous algebraic equations obtained after discretization, changing it not going to affect ne thing.

If your simulation is giving wrong results you need to check the simulation setup and not be concerned the linear solver.

If you provide some more data regarding your simulation setup maybe someone can help u.

 Zuixy March 14, 2011 04:43

Thx for the answer. I didn't get wrong reluts and i could fix the problem by doing more iterations. Due to the fact that i'll have to calculate some variations i thought i could improve the speed a bit.

But another thing:
I want to calculate the heat flux over the outer cover of a cylinder.
1. I was using a Area Averaged Report with the Boundary Heat Flux field function over the interface. The result was zero.
2. I tried the same but with a cylinder section which had a smaler radius as the cylinder. The result was also zero.
3. I tried a heat transfer report over the interface. It was also zero.

After that i thought about the reason and got two ideas.
1. It is to small to be calculated.
2. There is something wrong with the interface. But what? I impried the bodies as i designed and the In-place Interface was created by StarCCM.
Do you have any idea where the problem could be?

 alastormoody11 March 14, 2011 04:51

To increase the speed with which your solution converges you might try by increasing your under-relaxation factors

 willimanili March 20, 2011 11:24

Try to optimize your initial settings close to the solution you expect, that should improve your speed, too.

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