Mesh Refinement Tutorial 3.2

MFiX
#1

I am new to CFD and I am trying to run tutorial 3.2 with a finer mesh. When I try to use a uniform mesh of x=320 and y=960, I get the following error: ‘ERROR time_step.f:193 DT < DT_MIN. Recovery not possible!’.

I have increased number times I write to the VTK file as directed in the tutorial to 0.01 and 0.001 but it hasn’t helped: "On the Output pane, VTK sub-pane, change the write interval to 0.01".

Please help.

#2

Hi, have you solved this problem? I meet the same problem with you.

#3

If you really want to run with such a fine mesh, you should expect the time step to drop significantly. A few things to try:

  1. Change the initial condition (void fraction, initial velocity) to see it it helps convergence at the beginning.
  2. Use smaller DT_MIN, and hope that DT will climb back up once the flow passes the initial stage.
  3. Use ideal gas law instead of constant gas density.