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Old   September 21, 2008, 05:18
Default cfx time scale control
  #1
Kordou
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Hi again

I am modelling a double facade in cfx. My first model had a uniform grid of only hexas, and had been designed in workbench. In that model I had apply a time scale control of type "Local Tine Scale Factor" and with value of 0.2 and I hade also model it with buoyancy. I hade some successful runs.

Now I have made a new grid with inflation in ICEM, again only hexas. The grid has an inflation of 1.2 logarithmic on the walls. I am trying to run this mesh with the same setting on cfx, but it does not converge. I tried all the scale control options but still nothing. The mesh has a very good quality.

Could anyone suggest me a time scale control

Thank you

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Old   September 21, 2008, 18:42
Default Re: cfx time scale control
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Glenn Horrocks
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Hi,

For some types of simulations an expansion ratio of 1.2 is too much. Try decreasing it.

The CFX documentation has extensive discussions about how to obtain convergence.

Glenn Horrocks
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Old   September 22, 2008, 11:07
Default Re: cfx time scale control
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John S
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You might try using a physical timestep. I often get good convergence using a timestep about 1/3 of the advection time of my domain.
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