[Nick R]

Hi,


I was wondering if there is a way that you could set different residual convergence targets for different equations when using the adaptive time step. Is this possible? For example 1e-4 for continuity and 1e-5 for momentum etc. Thanks in advance.

[MUMMED]

I think there is a way
in solver control setting you can adjust convergence control criteria for continuity and momentum and turbulency separately.

[JuPa]

No you can't do this. You can however have different schemes for advection and transient.

[Lance]

Originally Posted by RicochetJ

No you can't do this. You can however have different schemes for advection and transient.

Actually, you can. I asked Ansys support this questions a few years ago and their reply was that for transient models the option was not exposed in PRE, but could be changed using CCL. There will be an error message but it can be ignored.

This example shows how to set a different convergence critera for an additional variable.

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-5
       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

[JuPa]

Wow, that's good to know. I take it then you must replace the CCL file in command line prior to running the simulation.

[Lance]

Originally Posted by RicochetJ

Wow, that's good to know. I take it then you must replace the CCL file in command line prior to running the simulation.

Yes, do it either at the command line or right before you save the .def in PRE. Note that for additional variables there is just one set of options, so it is not possible to have different convergence criteria for different AVs.