Dense Particle Entrainment
 

Hi all,

I am relatively new to cfd and am trying to model a turbulent compressible particle laden flow through a horizontally oriented cylinder. I am using an Eulerian Eulerian multiphase model (EMP) with the continuous phase being nitrogen (N2) and the dispersed phase being copper (mean diameter of 30 micron). I am using a k-epsilon turbulence model.

The issue I am running into is that gravity is causing the copper to fall to the bottom of the pipe and making the numerics to diverge. The pipe is about a meter long (diameter of 1cm) and the accumulation of copper begins about 0.2m down the pipe. Originally this was expected since copper is about 450x more dense than N2. However after reviewing experimental data of what I am trying to model, it is clear that the copper should be entrained within the N2.

At the inlet to the pipe, the copper and the N2 are moving at the same velocity (well above the velocity required for saltation) and the Reynolds # is about 30000.

I have also ensured that my mesh falls within the requirements for a k-epsilon model where the y+ of all the cells are all greater than 30.

I have employed several different multiphase interaction models to model the interaction between the copper and the N2: drag, lift, turbulent dispersion, virtual mass,particle induced turbulence, etc. and none seem to make a difference in the entrainment of the copper.

I am now considering adding a momentum source to the copper to allow the copper to stay entrained in the flow (assuming that the model is just not able to capture the physics of this flow). However this route seems a bit artificial.

I was wondering if there are any additional physics I could be missing or better yet some overall advice on what usually has to be done to entrain dense particles in a flow?

Any help would be greatly appreciated! Thanks!