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Old   September 18, 2008, 13:05
Default Under Relaxation Factors
  #1
Abdul
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In CFX Is it possible to set the under relaxation factors for mass, momentum... as in fluent? In the documentation it is given as we have to write a CCL file for this. Is there any direct method for controlling these factors...
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Old   September 18, 2008, 19:16
Default Re: Under Relaxation Factors
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Glenn Horrocks
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Hi,

Yes, you can set the URF for "fluids" (ie momentum and pressure together, but not seperately as it is a coupled solver) and the other equations using expert parameters.

However, unlike uncoupled solvers it is rare for these parameters to need to be changed in CFX. Usually people who want to change the URF parameters have more fundamental problems in the simulation (eg poor quality mesh, bad numerics or difficult physics) which should be addressed and then there is no need to fiddle with URF.

Glenn Horrocks
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Old   September 18, 2008, 23:56
Default Re: Under Relaxation Factors
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johnny
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If you are running steady state, the timestep is used to "relax" the case. The smaller the timestep, the more you are relaxing the solution.
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Old   September 23, 2008, 00:22
Default Re: Under Relaxation Factors
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sanjay pawar
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Hiiii In case of steady state u can go for lowest possible timestep.

In case of Unsteady step u do the following CFX-pre / create/ Expert object/ Expert parameters/convergence control/relaxation parameter

then u can adjust the values of relaxation parameters/
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Old   September 23, 2008, 10:13
Default Re: Under Relaxation Factors
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Abdul
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Thank you Very much Dear Glenn, Johnny and Sanjay for your valuable suggestions..
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Old   October 21, 2008, 02:16
Default Re: Under Relaxation Factors
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asral
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I have a problem, how the mentione of the under relaxation factors in FLUENT. please give me the information about this.

thanks.
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