Fluids

Fluids

FSI wont run when transient data table used for boundary condition (fluent)

    • jbsmart98
      Subscriber

      Hi,


       


      I am running a 2-way Fluid Structure Interaction (FSI) using Ansys Mechanical and Fluent, linked with system coupling.


      I have a pressure far field boundary condition and want to 'step up' the Mach number, then keep it constant for 20 timesteps, then step it up again, keep it constant for 20 time steps and so on...


      To do this, I have used a transient table, which is read by fluent and I have set it to be used in the pressure far field boundary condition.


      This works absolutely fine when I run fluent on its own. The FSI with system coupling also works fine when I use a constant Mach number in the boundary condition. But when I try to run the FSI using the transient data table, I get this error:


       



       


       +====================================================================+


       |                              NOTICE                                |


       | An exception has occurred and has been transmitted to the coupling |


       | participants.  These participants have been disconnected from the  |


       | coupling service.                                                  |


       +====================================================================+


       


       


       


       +====================================================================+


       |                      System Coupling Exception                     |


       +====================================================================+


       | Origin            : CFD (Solution 1)                               |


       | Error Code        : 20                                             |


       | Error Description :                                                |


       |   Exception encountered when the coupling service requested        |


       |   ChartableData->GetRootLevelName: Communication socket            |


       |   unexpectedly disconnected.                                       |


       +====================================================================+


       


       


       System coupling run completed with errors.



      Anybody know how to fix this? Alternatively, does anyone know another way to increase the inlet Mach number at set time points.


      Thanks for the help.

    • Stephen Orlando
      Ansys Employee

      Hi,


      Can you try using an expression to define the Mach number? The time, t, and timestep, dt, are available in Variables > Alias. You can also use an if statement in Functions > Conditional.




      Stephen

    • jbsmart98
      Subscriber

      Hi Steve,


       


      Interesting to see that feature, but is it in 18.2, or is that only available in the 19 versions?


       


      Cheers,


      Josh

    • Stephen Orlando
      Ansys Employee

      Hi Josh,


      Expressions were introduced in version 2019R1. Note that this is newer than the 19.x versions. I've confirmed that using expressions will work, so I recommend using a newer version.


      Best regards,


      Steve

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