[Zena27]

Hello all,
I have a problem where I have a laminar flow, and a moving mesh, and I want to solve it using pimpleFoam. It's a very slow piston motion. I'd like to solve it for a long time, so I need quite large steps. I just don't know what to change in the fvSolution to get this higher timeSteps.

I read here in the threads to use a first order scheme. Will it be accurate enough or how to even know this?

Also I read about using relaxation factors.. I have a question here, I know that relaxation factor multiplies the true solution by a factor that's why we use it in simpleFoam because we're not interested in the intermediate values, but here it's different. So how can we use relaxation factors in pimpleFoam?

Is it better to use adaptive time step or constant?

If you have any other suggestions to add, I'd appreciate it.