Fluids

Fluids

Fluent iteration doesn’t start

    • jFroh
      Subscriber

      Hi,


      I'm new to Fluent and I'm currently working on a packed bed, multiphase gas-liquid Fischer Trospch reactor in Fluent (species and energy enabled, laminar model). I've created the mesh and set up the simulation (using a UDF to model the reactions as hetergoneous reactions, 15 reactions in total) with all boundary conditions defined.


      After initializing the solution, I tried to start the calculation, but Fluent doesn't start the iteration and doesn't give an error message either. I don't know why this is and would be very grateful if someone has an idea what could be the problem.


      The mesh I've created has this size:


      Level   Cells   Faces      Nodes   Partitions


      0    135874    316351    48708       1


       


      3 cell zones, 16 face zones.


       


      Thank you for any help!

    • RK
      Ansys Employee

      Hello, 


      Can you please click on "Check Case" and see if there are any recommendations? 

    • DrAmine
      Ansys Employee
      very interesting: new to Fluent but using UDF for Fischer Tropsch. What does case check tell? How does the run task page look?
    • jFroh
      Subscriber

      Thanks for your replies, I get two messages from phase check:


      1) Boundaries and cell zones: Non-zero operating pressure set. This will be added to gauge pressure inputs.


         My operating pressure is 101325 Pa.


      2) Materials: Assign individual fluid Cps to polynomial functions of temperature.


         I defined the cp as constant, which might not be correct but I don't think that this prevents the calculation from starting to run.


      I attached a picture of my run task page. I wasn't sure how many interations are reasonable so I chose 1000.


      Thanks for your time!


      And yes, I'm working on a project that requires the use of a UDF to implement the kinetic model I'd like to use. I'm basing this on a paper that corresponds to the topic.

    • jFroh
      Subscriber

       Update: I was able to find the mistake, it was in the code of the UDF. Now the iteration starts but detects a floating point exception after a few iterations. If I'm unable to find a solution to that, I'll post here again.

    • DrAmine
      Ansys Employee

      Perfect! Please then create a new thread for that.

    • Tim Weber
      Subscriber

      Hi, I have the same issue. When I press calculate it just stays at 0% and never proceeds. I does not give me any error message and if I perform check case, all is good it says.

      I want to perform a transient calculation. The last message is updating solution at tim levl N...done. then nothing.

      At the end I have to forcefully shut-down fluent because it gets stuck without even starting

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