DISS causes simulation to diverge
 

Hello everyone

I am trying to run an unsteady flow in a simple volume - an inlet pipe and an outlet pipe connected to the same face of a cubic volume. I am using a pressure pulse as defined in a .dat file as my pressure inlet, and outlet pressure is constant at zero.

I know the boundary conditions are ok, because I have 3 different variations of my simple simulation and the first two converge easily. However, this simulation diverges at timestep 1 with DISS at 5.51E+17 and ENTH at 2.95E+05. All other residuals are 0.00E+00

When I run it as laminar it diverges at timestep 2, but the residuals are all 0 so I don't know what causes it.

Does anyone have any ideas?

Re: DISS causes simulation to diverge
 

try reducing the pressure under relaxation factor. say 0.8. default is 1. check whether PISO correctors are reaching to its limit and courant number (normally 100).