Fluids

Fluids

Convergence issue, how do I stop the number of iterations per step from reducing over time?

    • angusb1243
      Subscriber

      I'm relatively new to Ansys Fluent, I am attempting to run a simulation of a car exhaust into a box atmosphere to see how the emissions flow. I have set the outlet of the pipe as a velocity-inlet, and the end of the box as a pressure-outlet. I have attached my setup "run calculations" page as I think this is where the issue lies, any tips would be greatly appreciated!

    • Rob
      Ansys Employee
      In a transient model the solver will use up to the maximum (100 here) iterations per time step. If the convergence criteria are hit before the limit the solver will move onto the next time step. This is a good thing as we want to use as few iterations as possible per time simulated. If the model is stopping when you try and restart, ie "Calculation complete" check the Setting on the panel and check the maximum time. It's commonly overlooked.
      As an aside, if the solution is nominally steady state use that approach. With a transient case you need to run enough time steps to have completed the model, and the system may not reach equilibrium (or whatever end point you desire) for many time steps.
    • ABDCE
      Subscriber






    • ABDCE
      Subscriber
      Hello, I have a convergence problem in my calculation, and I know that I can solve it either by
      modifying the size of the elements of the mesh or if the deformation
      exceeds the limits, which is solved by passing from the force input at the displacement input.
      but how to go from force input to displacement





    • Rob
      Ansys Employee
      Displacement is from the moving deforming mesh. If the displacement is too great you need to reduce the time step.
Viewing 4 reply threads
  • You must be logged in to reply to this topic.