Hello,

I am solving a single phase, unsteady, rotating flow in a cylinder---just continuity and momentum equations.

What exactly does it mean when Fluent tells me my unsteady solution has "converged" if I set my residuals to say < 1E-5? I mean when I go to check continuity at a point in my model there are many places where it is not satisfied anywhere close to 1E-5. Is this an indication that my mesh is too coarse at these locations or perhaps I have chosen my inlet and exit boundary conditions inappropriately.

Any insight would be much appreciated!

hi, if you look carefully at the manual(paper or electronic), you will find that there are different definitions of residual, which will depend on the solver type firstly, i.e. segerated and coupled are different. Be sure to check what kind of solver and residual definition you are using.

Your solution is converged that means results are almost satisfied the citerion u set for the simulation. This residuls less than 1e-5 is only the difference between your present value and previous value. If you are not lucky enough, u could see you are diverging from the next iterations. This is called instability of residual. It may happen for unsteady turbulence case.

Alamgir