Divergence
 

Hello,

I encountred a problem of divergence with continuity, and velocity residuals, especially when I put a large number of iteration per time step. How can I solve to that? Thanks.

Re: Divergence
 

What is the problem you are trying to solve? what are ur Bcs, under-relaxation factors?

Re: Divergence
 

Hi,

I encountred a problem of divergence with continuity and velocity residuals, especially when I put a large number of iterations per time step (>=10). I should mention that this doesn't happen if small number of iteration is put. (1-5).

Even,I lowed the under relaxation factors of pressure (0.3-0.4), momentum (0.4)! Or changed the initial velocities, or turned off the energy equation for first iterations, in vain!

it gives this error message: Error: divergence detected in AMG solver: vof-1 and then: Error: floating point error: overflow Error Object: ()

What do you think, what can be the cause?

Thanks

Re: Divergence
 

Hi Safa, From what you have given here, it looks like you are trying to solve a multiphase problem. VOF-Liquid may suddenly shot up to a value that could have led to the divergence. There is no easy answer to this except continually experimenting with the URFs. With regard to the no. of iterations, is ur problem converging in each time-step when you reduce the no of iterations per time-step?