Fluids

Fluids

Error at node 0: Global Courant number is greater than 250.

    • kkamal
      Subscriber

      I'm trying a Volume of fraction multi-phased simulation with a helical shaped static mixer. However, when I run the simulation, it gives me the error stating that the global courant number is greater than 250. I have tried reducing the time-step size but it didn't really help much.

      This is my geometry

    • Rob
      Ansys Employee
      It means the time step is too big relative to the flow velocity and cell size. If the model is diverging the flow velocity will begin to become incorrect, accelerates and the solver eventually fails.
    • kkamal
      Subscriber
      thanks for you reply. What should I do to resolve the issue?
    • Rob
      Ansys Employee
      Check the mesh quality & size especially in small gaps. Work out the expected flow velocity through those gaps. The starting time step should be such that the flow takes 5-10 timesteps to cross the cell and each time step will converge in 10-15 iterations.
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