Appropriate particle to cell width

Submitted by jagan1mohan on Wed, 01/06/2021 - 11:02

Hello Friends, I'm working on a CFDEM setup in which a cube is filled with a few particles such that the particle to box volume ratio is 0.6. The fluid domain (please see attached images) has all cubic control volumes. I have tried two different cell widths.

1. cell width = 1.162*partDia. This is from the documentation that the volume ratio of the biggest particle to the smallest cell >= 3.
2. cell width = 3*partDia. This is from articles.

I'm using voidfraction divided model with the following properties.
alphaMin 0.01;
interpolation false;

When I see the voidfraction range for the fluid domain in paraFoam,
for (1): it varies from 0.038 to 1 as seen in fineMesh.jpg.
for (2): it varies from 0.27 to 1 as seen in coarseMesh.jpg.

What is happening here? How to decide appropriate cell width based on particle size?

Thank you,
Jagan Mohan.

Image icon coarsemesh.jpg31.6 KB
Image icon partbox.jpg88.17 KB
Image icon finemesh.jpg31.54 KB