Simulate particle/liquid flow in a converging geometry with MPPICFoam
 

Hello All,

This is Min, a Ph.D. in Petroleum Engineering.

I have been working on MPPICFoam during the past 3 months.
My focus is to apply MPPICFoam to simulate particle/liquid transport in the wellbore (a cylinder) with a perforation (it is a constricted geometry compared with the wellbore).

Please look at the attachment for the detailed geometry information.

Boundary conditions could be like this:
Inlet: fixed velocity pointing into the cylinder;
Outlet: fixed pressure (P=0);
Perforation: fixed velocity pointing out of the cylinder, which means the particle&liquid would flow outside through the perforation, which is exactly the source of the simulation problem.

Our simulation case has a wide solid/particle volume fraction range (from assumed even spatial distribution near the inlet, which can be 0-20%, to dense flow near the perforation (the constricted area), which can be 40-60+%)

Our Reynolds number could be 1e6, even 1e7, so it is a turbulent flow.

Then, I find that it is very difficult for MPPICFoam to handle the situation where the perforation fluid velocity is larger.
The error message is, the max. particle volume fraction is larger than 1 and then it crashes.

Q1: I set the packing limit to be 0.6, I don't know why the particle volume fraction could be larger than 0.6, even larger than 1.

Q2: When the perforation fluid velocity is small, MPPICFoam could handle this problem and the results could match experimental data very well. But if the perforation velocity is larger, then it means, the fluid will drive more particles to come to this constricted area simultaneously, then MPPICFoam will crash. Why? Compared with the dilute flow, MP-PIC should be more appropriate for the dense flow, yes?

Q3: I think I need to look into the source code to figure out why MPPICFoam could calculate a particle volume fraction larger than packing limit, even larger than 1, which is unphysical. But I don't know where to start?


Any comments and suggestions would be very very appreciated!

Thanks and best regards,
Min

Hello All,

I am still waiting for your valuable answers/comments/suggestions!

FYI, I think this related paper is worth reading.
Assessment of Different Discrete Particle Methods Ability To Predict
Gas-Particle Flow in a Small-Scale Fluidized Bed
Liqiang Lu,† Balaji Gopalan,†,‡ and Sofiane Benyahia*,†

If I were you, I'll try the same condition in a rectangle to check if the problem is caused by CFD grid.

Hello llq,

Thank you so much for your reply! Very appreciate!

I am wondering why you think I could use a rectangle instead of a cylinder to check where the problem is. I'm sorry I can't get your point. I am wondering whether you could explain more.

Thanks and best regards,
Min

Which version are you using, .com or .org?