Hello
I know that it is the basic assumption and a prerequisite in unresolved CFDEM that the particle diameter must be smaller than CFD cell size. It is recommended that that cfd cell should be around 10*particle diameter.
My question is related to size of cfd cells in all the three directions (x,y,z). The main thing one should keep in mind is that the solid fraction in each cfd cell (which is a volumetric quantity) should never become 1 because it will result void fraction=0 and the goverining equations become invalid. However, one need to resolve the cfd flow in details especialy in turbulent flows where lower Yplus values is desired and which can cause y-direction cell to become larger than particle diameter. I was wondering if one can use smaller (than particle dia) cfd cells in y-direction near the walls in order to have lower yPlus values, provided the cell size in x and z directions are larger (much) than particle diameter. Providing such an arrangement would fulfill the both criteria as one get to resolve the boundary layer properly and at the same time cells are not fully covered with particle as z and z dimensions are quite bigger than particle diameter and solid fraction in each cell is always less than 1 thus condition is unresolved CFDEM is satisfied and never violated.
What do you think, is it possible to do so?
Best Regards
Atul Jaiswal