Mesh Size for Particle Study

Hi everyone,

 

I made a CFD simulation of a geometry with water and wanted to know how the separation characeristics of the CAD model looks like with gas bubbles. I found out that the separation efficiency of the model is strongly depending on the mesh size, even if the fluid chatacteristics are not (pressure, velocity, ...). 

 

Is there any way to make an estimation or even better a calculation of the minimum mesh size that is needed to have constant results of the particle study also when refining the mesh? Or are there any other boundary conditions to pay attention to?

 

Thanks a lot in advance for your help!