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Lance December 14, 2010 08:24

[CFX] Set convergence level for additional variable
 
Hi,
Im running LES and have set my convergence level to 1e-6 which the solver reaches within a couple iterations. However, I have an additional variable and it takes about 10-15 iterations per time step for it to reach 1e-6.

So, in order to speed up my simulation, I want to set a lower convergence level for the additional variable. Is that possible? I know that Fluent has the option to specify convergence level on each equation, it would be great if CFX also had that option.

Lance December 15, 2010 08:22

Update:
got some help from support, and yes, its possible to have different convergence criteria for AVs. Just edit the CCL like:
Code:

FLOW: Flow Analysis 1
SOLVER CONTROL:
  Turbulence Numerics = First Order
  ADVECTION SCHEME:
    Option = High Resolution
  END
  CONVERGENCE CONTROL:
    Maximum Number of Coefficient Loops = 10
    Minimum Number of Coefficient Loops = 1
    Timescale Control = Coefficient Loops
  END
  CONVERGENCE CRITERIA:
    Residual Target = 1.E-6
    Residual Type = RMS
  END
  EQUATION CLASS: av
    ADVECTION SCHEME:
      Option = High Resolution
    END
    CONVERGENCE CRITERIA:
      Residual Target = 1.E-3
      Residual Type = RMS
    END
    TRANSIENT SCHEME:
      Option = Second Order Backward Euler
    END
  END
  TRANSIENT SCHEME:
    Option = Second Order Backward Euler
    TIMESTEP INITIALISATION:
      Option = Automatic
    END
  END
 END
END

There will be an error message in CFXpre: "Convergence criteria....not physically valid", but just ignore it, and it will work - at least it does for me.


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