[Danny_]

Hello,
I'm trying to simulate a multiphase system represented by a hexaedral vessel partially filled with water which is later to be charged by solid particles injected from the upper part. The remaining part of the vessel is obviously filled by air at t=0.
To do that, I coupled the interFoam native solver with the src/lagrangian/intermediate directory, as described in "https://www.foamacademy.com/wp-content/uploads/2016/11/GOFUN2017_ParticleSimulations_slides.pdf" and managed to correct all the errors found.
The simulation runs fine; however, the particles injected once fallen below because of gravity, stop at the water-air initial horizontal interface and never cross it. Therefore, I am not able to simulate the mixing process I am interested at for this system.
So far I changed repeatedly different parameters I supposed relevant (U_O of particles injection, rho.air, rho.water, nu.air, nu.water, parcelsPerSecond) but nothing works.
I suppose that the problem is that a drag model also for the lower phase which is not interested by the initial injection event cannot be set in the kinematicCloudProperties dictionary (otherwise the simulation immediately crashes)
Any suggestion to solve this issue would be highly appreciated.
Kind Regards,
Danny

[Danny_]

Remaining files

[JulioPieri]

Dear Danny,

I haven't worked with interFoam coupled with LPT, however I'm using swak4Foam together with the twoPhaseEulerFoam - which is also multiphase. Since I don't have the correct solver, I'm unable to reproduce your case here. Do you have any pictures of the particles "sticking" to the interface?

Things I'd try if this were my case:
- change drag model to sphereDrag, or remove it completely
- change base pressure of your case to 1e5
- remove pairCollision model to simplify the solution and speed up the debugging.
- include particleTrap function
- introduce a disturbance on the alpha.water field and see if the particles at least oscillate together with the interface (suggesting a "crossing" difficulty) or if they are simply maintaining position (thus unrelated with alpha).
- add an interface force to pull particles into the water - this might be unrealistic but may be a way to bypass this issue.

I also wouldn't discart implementation issues, since this is a custom solver. Try running swak4Foam for debugging as well.

Lastly, I recently had a problem where my particles wouldn't move at all with the velocity field. After long hours of trying, I decided to simple reset the case and start from another one and that solved the issue. Sometimes, and I don't know why, this simply works.

Edit: also, double check you mu field in the kinematicCloud file. Since the drag is calculated from that, make sure you're getting the correct value. I faced and solved a similar problem yesterday, right after replying.

Best regards

[frantov]

are you aware of the solver mppicinterfoam ?

it is available on the openfoam.com version