Fluids

Fluids

Newton’s method warnings

    • abbas
      Subscriber

      Hello every one,

       

      I generated an RGP table and during the process, I received the following warning.

      How or where can I change the Newton iteration underrelaxation factor. 

       | Temperature : "Constitutive Relation Under Relaxation"             |

       | Pressure    : "Newton Pressure Under Relaxation"

       

      Best regards

      Abbas

    • DrAmine
      Ansys Employee

      Does the situation persist?

    • abbas
      Subscriber

      Hi,

       

      Yes, the situation persists. Therefore I am looking to reduce the relaxation factor.

      Could you please let me know, how can I do that?

       

      Thanks

    • DrAmine
      Ansys Employee

       Copy paste here the CCL of your binary mixture (right click on it and edit in command editor then copy).

    • abbas
      Subscriber

       

      LIBRARY:

      &replace MATERIAL: CO2

      Binary Material1 = CO2V

      Binary Material2 = CO2L

      Material Description = Carbon Dioxide CO2

      Material Group = User

      Object Origin = User

      Option = Homogeneous Binary Mixture

      SATURATION PROPERTIES:

      Component Name = CO2L

      Option = Table

      Table Format = TASCflow RGP

      Table Name = Dcfx/CO2-high.rgp

      END

      END

      END

       

       

    • DrAmine
      Ansys Employee

      Add following lines under the line containing Option =Homogeneous Binary Mixture:

       Newton Pressure Criterion = 1[Pa] (Default)

       Newton Pressure Iteration Limit = 150 (Default)

       Newton Pressure Under Relaxation = your value (1 is  Default)

       

      This would add the under-relaxation of NR-P. If you do not understand what is the meaning of Newton Raphson and why is it required then check some references. In general, one has to ensure that every single line in the setup is correct before starting under relaxation this numerical scheme.

       

      I hope this helps. I leave feedback questions for other community members. 

       

       

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