EDEM force scale factor

Joshua García

Hi all;
I keep working on a simulation coupling EDEM and Hyperworks CFD and I still have problems. I am doing a simulation of non-spherical particles and I have doubts with 3 parameters.
In the EDEM simulation I have used a scale factor x2 in the particles as specified here:

In Hyperwork CFD I don't know if I should put 2 or 0.5, because if I put 2 the simulation does not work.

Another question is whether, as is my case, I use a material with 6 different particles, in this section what diameter should I put?

 

Thanks

RWood

Hi Joshua, 

The Ratio value in EDEM will simply scale the particles by the entered length scale. If your particle is defined as having a radius of 1mm, a ratio of 2 will create particles of radius 2mm in EDEM. Scaling by a fixed value of 2 would be no different to recreating your particles with double the length scales and using a Ratio value of 1. In an ideal world you would leave the Ratio at 1 and create your particles at the correct scale, if you are only using a fixed size distribution, but it doesn't really matter.

The 'EDEM force scale factor' in Hyperworks CFD has a totally different purpose. It is useful if you want to scale the drag/buoyancy forces being calculated on the EDEM particles. The intended application for this is if you are using a coarse-graining method (or similar) and intend your EDEM particles to represent more than a single particle. For example, when modelling powders it is not possible to model billions of individual particles in EDEM (yet!) so you may choose to model millions of scaled-up particles instead. Your particles in EDEM might then be say 10 times larger than they are in reality and so you need to account for drag and buoyancy at the 'true' particle scale, as opposed to the EDEM particle scale. This has nothing to do with the Ratio value in your first image. 

If you take a look at the attached pdf and videos, it should clear things up a bit. I made the videos and PDF as an example for this type of application, with the EDEM-Fluent coupling, a long time ago. I expect the Hyperworks CFD scaling would work the same but you would have to check with them to be certain.

Cheers,
Richard

scaleUp.zip