How to estimate weight and porosity in the bigParticle model

Submitted by Nico on Thu, 01/16/2020 - 22:02

Dear all,
I am new at CFDEM. I've been having trouble understanding the meaning of weight and porosity in the bigParticle model.
I have tested several cases with lots of combinations between these two parameters and I've observed that they have a huge influence on the final result. Moreover, when I change the mesh refinement, the values that I've used for weight and porosity have a different effect on the simulation.
So, the best way to resolve this issue is to try to estimate the values instead of randomly try them until my result is good enough.

But I didn't understand how can I calculate those values. I've looked at the code and it looks like the weight is directly multiplied by the volume of the sphere. As for the porosity, they calculate the cubic root of it and multiply it by the radius. Does that mean that I am directly increasing the volume and the radius of my spheres by increasing the values of the weight and the porosity? If so, how much should I increase those parameters so that my case is realistic?

By the way I am using an alphaMin of 0.1. The simulation consists of a 250 spheres in a fluidized bed problem.

Any information is appreciated.
Cheers