[Mohsin]

Hello

I am doing 5 simulations. what i will do is to just change the velocity for every simulation and compare the outcome of the results. But what happens is that if i change the velcoity it takes more iterations to converge and also i have to reduce the convergence criteria.

Do i need to have same iterations, same residual criteria and same under relaxation factors for comparison of my simulations or Is it posisble to give a small change to these parameters as long as the surface integrals and some other convergence criterias are fulfilled?

Thank you for your time.

Mohsin

[Chris D]

Originally Posted by Mohsin

Hello

Do i need to have same iterations, same residual criteria and same under relaxation factors for comparison of my simulations or Is it posisble to give a small change to these parameters as long as the surface integrals and some other convergence criterias are fulfilled?

No. Iterating and using under relaxation are just a means to an end. They do not influence the solution you eventually obtain, so if your solution is actually converged, then there should be no problem.

[-mAx-]

For the same geometry, if you are modifiying the velocity, then you are modifiying also the Reynolds-number. Then you need to modify also turbulence BC (if you are in turbulent domain)
I can imagine that it takes more or less iterations to converge if you perturb the inlet BC.
But your goal is getting a converged solution, that's all.