hi, all:

When I am using the VOF to model the oscillation of the drop, an error happened:

"Too many VOF sub-timesteps, the velocity field is probally diverging"

What does this mean? what should I do?

Thanks a lot

Lichun Dong

Simply your time step is too large. Try the procedure that follows:

1.Start the simulation with a really small time step dT1 allowing convergence within 20 iterations per time step.

2.Run a number of timesteps to get the flow going.

3.Save converged data.

4.Specify a very large time step dT (6 orders of magnitude larger than originally, at least)

5.Fluent should pass an error message (like the one you said) detailing the number N of VOF sub time steps needed to cover the specified dT.

6.Thus, the VOF sub time step can be computed as tau=dT/N

7.Now continue the simulation with a time step within the limit of 10-20 VOF sub time steps.

Hope this will help...

Edi.