Unsteady Wall Statistics

    • CaptainConvergence

      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

      No one has any idea?

    • Karthik R


      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?




    • CaptainConvergence

      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,


    • CaptainConvergence

      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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