Fluids

Fluids

Unsteady Wall Statistics

    • CaptainConvergence
      Subscriber

      Hi all, I have lost 6 days of simulation in a cluster because Fluent didn´t collect statistics for my wall shear stresses.

      As you can observe in the attached images I have selected the options to collect statistics for wall statistics but when I check my contours of Mean X-Wall Shear Stress, my values are 0, meaning that it didn´t collect any statistical data. It is not an inviscid case and I have values for the instantaneous x-wall shear. However, I have data for the Mean Pressure Coefficient, which is inside wall statistics.


      I have attached 3 images to show what is going on:


      Unsteady Wall Statistics: Mean X-Wall Shear Stress, it is zero.



      Wall Fluxes: X-Wall Shear Stress, there are some values therefore they are not zero.



      Unsteady Wall Statistics: Mean Pressure Coefficient, it has collected the statistics properly.




      I am very confused with this, why isn´t fluent collecting statistics of my wall shear stresses??

    • CaptainConvergence
      Subscriber

      No one has any idea?

    • Karthik R
      Administrator

      Hello,


      Is this something that happened just this once? Or have you observed this behavior in any other case? 


      Also, do you see this behavior for any other flow variable?


      Thanks.


      Best,


      Karthik

    • CaptainConvergence
      Subscriber

      Hello Karthik,


      Thank you for your answer!


      This has happened twice to me and I wouldn't like to launch a third simulation without knowing what it's going on.


      Apparently it only occurs with the shear stresses and skin friction coefficient because I have unsteady wall statistics (wall fluxes) for the rest of variables (Pressure coefficient, surface heat flux, surface Stanton number, surface Nusselt number etc). I am using ANSYS Fluent 2019 R3.


      Kind regards,


      César.

    • CaptainConvergence
      Subscriber

      I would appreciate any tip regarding how to fix this issue since I don´t really find any error in the set up

    • Rob
      Ansys Employee

      What happens if you create a custom field function for each of the missing fields?  No need to run for 6 days to test, 10-20 time steps will do it. 

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