Recommendation to simulate particles differing in size (and shape)

MFiX
1

Hello,

I am trying to simulate a case in which sand (dp~0.4 mm) and biomass particles (~13 mm equivalent diameter) are in the same reactor.

What could be the best way to define the mesh and CGP parameters for a correct hydrodynamic simulation?

I am trying to set a mesh to be around the particle size of the biomass particles and then diffusse the information to around 3 times that biomass particle size. That would require large statistical weights on the sand to respect so that around 3 sand particle diameters fit in a cell. In any case, the results I am getting show a piston-like behavior of the bed, which is far from realistic.

Reading some papers I found this coupling of CGP with GSP. That is, several glued particles are used to represent a biomass particle. I think that could be useful in my case, but I see no direct way to implement it rather than programming it myself. Do you have any recommendations or routines?

https://aiche.onlinelibrary.wiley.com/doi/full/10.1002/aic.17211

Any piece of advice or recommendation is highly appreciated.

Thanks!
Eduardo

2

Hello,

Does someone have a piece of advice regarding this?

Thank you!

3

Did you consider PIC or TFM instead of CGP? Your use of sand might speak in favour of something more “eulerian”, instead of tracking each tiny particle. What will be the end-takeway from the simulations?

4

Thank you for your answer.

My idea is to track the motion of the biomass particles. If I use PIC or TFM I would need to use the hybrid method, which is in the code but not given support.

That is why I decided to move to CGP, but the large difference in size complicates things and I do not know what are the most appropriate conditions for such a large differences in size.

5

You mean the exact motion of particles? You can do those things with TFM and PIC also, given a good mesh resolution. PIC will also gives you particle residence time.

6

Yes. The point is that I have a bed of sand particles and only 2 biomass particles on the system and I want precise information on the motion of those particles.

In my understanding, I cannot do that using PIC or TFM without using some kind of DEM for the big biomass particles.