[achat]

Hello:

I was wondering if anyone encountered the following, rather wierd, problem and if anyone could offer help/suggestions. I am using FLUENT.

This is a low pressure CVD problem of fiber coating with surface reactions. The solution is steady state. The 3D equation being solved are momentum, energy (with radiation) and a few species concentrations. For a few cases what I find is that when I restart a seemingly converged solution without changing anything, the steady state solution converges to a different state. Before the restart, the seemingly converged showed all traits of convergence: the weight gains had plateaued out, the residuals were small (<1e-4) and plateaued and so on. Also if I allow the seemingly converged solution to run much longer without interruption it would remain in the same (seemingly) converged state.

Clearly interrupting and restarting is doing something; as if waking the solution out of a metastable state. Has anyone encountered such a problem? What I also find is that for these cases when I restart, the residuals spike quite a bit although I am not changing anything in the restart operation. This too is surprising.

Thanks

Athan