[TPernatsch]

Hello everyone, I'm trying to simulate a vertical tube in OpenFOAM using the MPPICFoam solver. My fluid and my particles enter the tube on the upper (in the Z direction) face (inlet) and are supposed to flow downward, exiting in the bottom face (outlet). The boundary conditions for the particle-wall interaction is that theycan escape on the outlet while having a rebound bc with the external walls and the inlet. The problem is that, when I insert the particles (after the flow is fully developed) they instead try to go upwards, resulting in they being stuck on the inlet face. I tried basically everything but it doesn't seem to work. My Courant is always <0.8, the residuals are controlled and the simulation doesn't crash. Moreover, looking at the log file of the solver, it seems that the particles exiting my domain are one or two orders of magnitude higher than the ones entering the system:

Cloud: kinematicCloud injector: model1
    Added 2 new parcels

Cloud: kinematicCloud
    Current number of parcels       = 1267
    Current mass in system          = 0.00031675
    Linear momentum                 = (-2.04196e-09 9.61085e-09 0.000279082)
   |Linear momentum|                = 0.000279082
    Linear kinetic energy           = 0.00150784
    Average particle per parcel     = 7.95239e+07
    Injector model1:
      - parcels added               = 1267
      - mass introduced             = 0.00031675
    Surface film:
      - parcels absorbed            = 0
      - mass absorbed               = 0
      - parcels ejected             = 0
    Parcel fate: system (number, mass)
      - escape                      = 74488, 0.018622
    Parcel fate: patch (walls|inlet) (number, mass)
      - escape                      = 0, 0
      - stick                       = 0, 0
    Parcel fate: patch outlet (number, mass)
      - escape                      = 0, 0
      - stick                       = 0, 0
    Min cell volume fraction        = 0
    Max cell volume fraction        = 0.00141472
    Min dense number of parcels     = 2.82697

I'll leave my case attached below, but it's a very simple one. Unfortunately, my mesh is too heavy, even compressed, for the standards of this forum, so I'll just leave here an image of it.

Does anyone have any ideas about what could be the problem?

[TPernatsch]

Hi everyone, I finally solved the problem.
The cause of the strange behaviour was the packingModel which you have to specify from the kinematicCloudProperties file. Setting it to none (I haven't tested with explicit) fixes the problem.