[MachZero]

I copied this thread from the general forum since i am using STAR-CCM+, but not sure if this is a CCM issue or a CFD issue.

I am currently running a study where i am looking at particle deposition. Particles are very small, in the 1-10 micron range. I have gotten baseline results and everything seems reasonable. I am running a mesh sensitivity study where i refine my mesh and prism layers. I have two geometries, one is a small tube, and the other is a larger tube.

Small tube (running SST, but flow is laminar): What i am seeing is that, for the small particles on the order of 1 micron, the more I refine, the amount of deposition is reduced. The deposition isnt stabilizing, even with a very fine mesh. At 4 microns, things stabilize at the 1st refinement of mesh.

Larger tube (running SST, flow is turbulent): For 1 and 4 micron, particle deposition continues to decrease with mesh resolution, but at 6 micron it is stabilized through all meshes.

I ran a timestep and particle count sensitivity study, and both show that my results do not change with these factors.

What could be causing the continued decrease in particle deposition, without stabilizing. Am i going about this mesh sensitivity wrong? Or am i forgetting something?

Running in STAR-CCM+ 18.06.

[koful]

I think you should not decrease the mesh size too much. mesh size to particle size ratio should be above 10 (rule of thumb). If you further reduce the size for larger model It will give unstable results also.