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-   -   Solid Timescale Control (http://www.cfd-online.com/Forums/cfx/24435-solid-timescale-control.html)

Parthipan August 22, 2007 09:09

Solid Timescale Control
 
Dear all,

I am modelling a solid-solid CHT model in CFX. It consists of an inner volume and an outer bounding volume. The inner volume is the source of heat and I want to see the heat transfer in the outer volume. I have specified the inner volume as source with the Total source value in Watts.

After Performing a steady state calculation, I find that the temperature is very high than expected using a Auto Timescale in the Solid Timescale Control Tab.

I did the calculation again with the following settings with different values of 1s, 10s and 50s

Output control -> Solid Timescale Control -> Physical Timescale -> ___

These too gave a result far away from my expected results.

This time, I tried the calculation agian with

Output control -> Solid Timescale Control -> Physical Timescale -> 0.1 s

Now the Temperature is very near to my expected values.

1. How could I come to a conclusion with my Physical Timescale for the solid?

2. What if in a new case, I don't know the expected temperature to compare with?

Waiting for your replies.......

Thank you.

Glenn Horrocks August 22, 2007 18:10

Re: Solid Timescale Control
 
Hi,

Are you sure it has fully converged? In CHT simulations activating the imbalance convergence criteria is often useful. This often converges much slower than the residuals for CHT simulations.

You can judge whether it is going to have an effect by looking at the global imbalances in the output file.

Glenn Horrocks

Parthipan August 24, 2007 10:07

Re: Solid Timescale Control
 
Hai Glenn,

All the solutions have converged. What I wanted to do was a transient simulation. I wanted a initial file for my transient simulation, which had to be done by a steady state simulation. When I apply the same boundary conditions and run the simulation, the temp. shoots up to a very high value at the point of convergence. In advice from one of my collegaue I have taken off all the sources and done a steady state solution. And this I have used it for my transient simulation.


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