Fluids

Fluids

The fl process could not be started.

    • eduardo.barrientosv
      Subscriber

      Hello everyone,

      I am running a simulation of a half wing, using the model of k-w, SST. With air properties at an altitude of 2400 m.

      The quality of my mesh is, skewness = 0.86 and orthogonal quality = 0.17. At first, I had had problems with this simulation, it used to stop iterations and close everything abruptly, showing the error: "failed in handling fluent message". 

      My solution for this was to export the case and to run my simulation by standalone. But now, the problem is that simulation stops at iteration 154, showing the next legend.

      " The fl process could not be started.
      MPI Application rank 0 exited before MPI_Finalize() with status -1"

      I would appreciate if someone can give me an answer or an idea to fix this problem.

    • Nikhil Narale
      Ansys Employee

      Hello,

      Are you using parallel-processing? If yes, can you try to run it in series?
      Though this is not a reasonable suggestion, but can be a good starting point. Let me know if this works.

      Thanks,
      Nikhil

    • eduardo.barrientosv
      Subscriber

      Hi Nikhil,

      thank you for your response. I have used serie-processing as you recommended me, but the result is the same. 

      The simulation stopped (at iteration 32) and shows the following legend, "the fl process could not be started".

      I would like to know what I am doing wrong to fix this problem ¿Could you help me again, please?

      Note: In my simulation in cell zone conditions only appears fluid and not solid, I have seen videos where appears solid and they use it. My doubt is, if this cell zone condition could be the problem.

       

    • Nikhil Narale
      Ansys Employee

       

      Okay, interesting. Can you share the screenshot of the complete error message? Are you using any UDFs? 

       

      Cell zone conditions depend on the physics involved in the problem. I don’t think it has anything to do with this error. 

      However, it seems that this error may also show up if the solution is diverging or the mesh is of a poor quality. Can you also check on these things? 

       

      Nikhil 

       

       

       

    • eduardo.barrientosv
      Subscriber

      Thanks Nikhil,

      sorry for delay. About  mesh quality I am considering skewness and orthogonal quality with values of;

      Skewness = 0.86 and Orthogonal quality = 0.17.

      Considering  the parameters my mesh is acceptable, I upload the image where is shown the legend that fluent shows when it stops. Also, about your question if I am using UDFs, for this case I am applying some equations to help the simulations. I use four equations with a total of 1500 iterations, being 700 of first order and the rest of second order.

      Do you think that my mesh quality is not good enough?

      This es the legend that fluent shows, as you can see at the iteration 32 stops. 

       

    • Rob
      Ansys Employee

      I may question the resolution in the area of interest but the cell quality looks good. I'm slightly suspicious of any monitor that flatlines in under 10 iterations unless it really is a box with symmetry around the perimeter! The velocity residuals are also a lot lower than I'd expect that early in the solution. 

      Can you check RAM usage, and confirm if you're running over a network. There doesn't look to be anything causing a problem in Fluent that's solver related, so it may be external. 

    • eduardo.barrientosv
      Subscriber

      Hi Rob,

      thank you for your response. I checked the RAM usage and it was of 25%. Sorry, but I don't know exactly what means "running over a network". I made another iteration turning off the web and the next happened. (images uploaded)

      I have a doubt, those flat lines that you mentioned, are like that because a parameter that I introduced. I mean, maybe values that I am putting are making these lines being flat at first.

      What do you recommend me to do?

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