Fluids

Fluids

Negative Cell volume detected

    • Jpra93
      Subscriber

      Hello, I'm in process to simulate a Michael Banki turbine with ansys fluent, I made a sketch (2D) to simulate the profile of the turbine, but when I run the calculation, its stop and show the message "Negative Cell Volume detected", I read about it, and I think that can be the remeshing process but dont be sure. 


       

    • Jpra93
      Subscriber

      now I'm triying to simulate another form, with a rectangular domain, but even with those geometry i have the same problem that before, i found that the domain is the problem,  on the dynamic mesh i set with the deforming type zone, i dont know what can i do to sovle the problem, please help!!!, i put a image of the problem.

    • raul.raghav
      Subscriber

      Did you try using a lower timestep? Negative volumes are usually caused due to a larger timestep or tight smoothing criteria. Did you look into these points?

    • Raef.Kobeissi
      Subscriber

      When it comes to dynamic meshing I found that tetrahedral meshing is better than hexahedral mesh especially in avoiding negative cell volumens.

    • Jpra93
      Subscriber

      yes , I did that, but i cant decrease more the timestep because the iteration process take to much time and never end.

    • Jpra93
      Subscriber

      I used hexaedral and tetrahedral mesh. but  in both cases the mesh fail. 

    • raul.raghav
      Subscriber

      Could you attach the workbench archive file here so that we could take a look at the settings? If you're not sure how to archive the workbench file, check: saving and sharing workbench archive file

    • Jpra93
      Subscriber

      Here it's the file, thanks for the help.


      Jorge

    • Raef.Kobeissi
      Subscriber

      Hi,


      I checked your case and it is set up incorrectly. I recommend you to use the Sliding mesh method instead of dynamic mesh for this particular simulation. Check my tutorial:


    • Jpra93
      Subscriber

      But on the Sliding mesh method, speed is a know parameter, and i have to obtain this parameter to calculate the power generated by the turbine, how can i do that?, it's appropiate use the sliding mesh method on this case?. thanks.

    • Aparna
      Subscriber

      I am also getting negative cell volume error for scroll expander simulation. i couldn't solve it. kindly help me. there is no option for sliding mesh method.

    • Rob
      Ansys Employee

      You'll need to separate (and not connected) fluid regions. If the cells are connected over the sliding interface it'll do something interesting with the mesh.

    • Aparna
      Subscriber

      differentiated them at the time of modelling. still im getting the error. i could identify the error location but couldn't correct them. how to correct them.


       

    • Rob
      Ansys Employee

      Sorry, I'm not sure what you mean by that. You will need two zones (stationary & rotating) as per the tutorial. Can you check the mesh quality in Meshing just incase that's where the problem is?

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