Learning Forum

[reza121]

Dear Dr. Amine,

Will you please reconsider this problem now that the photos are uploaded and hopefully the problem is clearer?

All the walls (screen wires) are set to "trap" the particles in their DPM setting tab. They are solid walls and neither the flow nor particles penetrate them.

The issue is that even though the flow parameters show an identical trend with all the different mesh resolutions (scatter plot of flow z-velocity on a line according to one of the uploaded photos or skin friction factor on the walls), I am getting different numbers of trapped particles at the walls with different mesh resolutions in either vicinity of the walls or away from the walls. As I explained earlier in the previous posts, using the "body of influence" meshing feature, I give fluent meshing two mesh element sizes: one in the vicinity of the walls (called vicinity region) and one away from that (which I call up/downstream)

Here are some of the particle trap results for different mesh resolutions:

1- up/downstream 16e-6 , vicinity 4e-6.   # trapped= 50/60

2- up/downstream 8e-6 , vicinity 4e-6.   # trapped= 35/60

3- up/downstream 4e-6 , vicinity 4e-6.   # trapped= 26/60

In the studies above, I kept a constant mesh size for the vicinity region and changed the mesh size in the up/downstream region only. Also, in another study that I carried out earlier, I kept the up/downstream mesh size constant and changed the vicinity mesh size and the DPM results still change drastically. In the photo below, you can see better what I mean by vicinity and up/downstream regions.