Fluent iteration doesn’t start

- July 14, 2020 at 12:49 pm
  
  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!
- July 14, 2020 at 2:20 pm
  
  Rahul Kumar
  Ansys Employee
  
  Hello,
  
  Can you please click on "Check Case" and see if there are any recommendations?
- July 14, 2020 at 5:04 pm
  
  Amine Ben Hadj Ali
  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?
- July 14, 2020 at 5:34 pm
  
  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.
- July 14, 2020 at 9:44 pm
  
  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.
- July 15, 2020 at 6:30 am
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  Perfect! Please then create a new thread for that.
- November 25, 2022 at 10:01 am
  
  tweber
  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