Is it possible to retsrict the motion of one particle type while seconds not?

Submitted by atul2018 on Thu, 12/30/2021 - 13:23

Hello All

I am wondering if it is possible to restrict the motion of one particle type and seconds not?

Let me explain what I want to do: I want to create a bed of larger particles (type-1) and then inject small particles (type-2) with flow from inlet into the created bed. As per the experiment, the bed should be compeletely stable and shouldn't move at all, only small particle should get transported and get infiltrated into the bed. To achieve this, firstly, I perform pure DEM to create the bed (with Type-1particles) and then inject type-2 particles from inlet with flowing water (CFD-DEM simulation), somewhow I see some bed particle also get transported, which I dont want.

I think it is best if i can somehow restrict the motion of bed particles (type-1) while type-2 particles should move without any problem. I was thinking to perform nve integration on only one type of particles but I am not sure if it is possible. Do you have other ideas/suggestions to do this?

Best Regards
Atul Jaiswal

Forums:

mschramm | Thu, 12/30/2021 - 21:36

Hello,
You can add your bed and before you add the second particle type, create a group called 'bed'. Then apply the fix 'freeze' to the 'bed' group. This will keep the bed from moving at all. You need to make sure the fix freeze is after your fixes to the cfd-dem coupling as fixes are performed in order. So if the fix freeze comes before the cfd-dem coupling fix, then cfd forces would act on the bed while particle information would not.