Learning Forum

[Conor Mc Carry]

I am using a DPM fluent model with injections at a surface inlet to simulate particle injections throught a vent downstream to replecae particles in air. I am using a transient case K-omega SST witha inlet velocity of 2.5ms. My problem is that im having difficulting completing a mesh independance study as my results vary too much. Should I complete the refinment as steady case instead? Im using a report definition to record the DPM concentration on a iso clipped plane at the vent entrance to calculate the ratio of DPM concentrations passing through the vent compared to the amount at the injection surface, this ratio is the value im trying to investigate as I carry a my mesh refinement. But I cannot seem to get a mesh that has a less than 1% change compared to the prior value. 

 

Any insight would be greatly appreciated.

[Rob]

What are you trying to find out? 

[Conor Mc Carry]

I'm trying to find how much DPM concentration passes through a vent in a study to reduce DPM concentration with various vent designs. I am tring to do a grid independance study, but my mean value for DPM concentration changes so much between each mesh. Im using a 3D domain with meshs with cells of, 128k, 234k, 542k, 771k, 949k. Do I have to use a steady model for the mesh independance study instead of unsteady?

[Rob]

You need to look up what the DPM Concentration actually means: it's not a good measure. What may be a better measure is how much mass enters and then leaves the domain, and steady should be sufficient depending on the flow field.