[tomf]

Hi all,

I am trying to run a simulation where parcels are manually injected into the flow, using some randomly generated position within the domain. The number of parcels does not change during the simulation and I want to keep track of the parcels that stick to either a building or the ground. After some time, all parcels either stick or they escaped through the domain boundaries. The weird thing is that the cumulative number of stuck parcels increases during the simulation, where it seems that stuck parcels are counted over and over again. This seems incorrect, or is this behavior expected?

I can work with escaping parcels at these boundaries, which does seem to work ok as at least the numbers add up, but for visualisation, I rather have stuck parcels.

I used icoUncoupledKinematicParcelFoam from version 1806 with a flow field calculated using simpleFoam.

Time = 0.995

Evolving kinematicCloud

Solving 3-D cloud kinematicCloud
Cloud: kinematicCloud
    Current number of parcels       = 143545
    Current mass in system          = 0.531278
    Linear momentum                 = (0 0 0)
   |Linear momentum|                = 0
    Linear kinetic energy           = 0
    Injector model1:
      - parcels added               = 226800
      - mass introduced             = 0.571889
    Parcel fate: system (number, mass)
      - escape                      = 83255, 0.0406116
    Parcel fate: patch Building (number, mass)
      - escape                      = 0, 0
      - stick                       = 12637052, 38.7247
    Parcel fate: patch Ground (number, mass)
      - escape                      = 0, 0
      - stick                       = 66708034, 264.427
    Parcel fate: patch Top (number, mass)
      - escape                      = 0, 0
      - stick                       = 0, 0
    Parcel fate: patch Domain (number, mass)
      - escape                      = 83255, 0.0406116
      - stick                       = 0, 0
    Rotational kinetic energy       = 0

ExecutionTime = 506.1 s  ClockTime = 509 s

Time = 1

Evolving kinematicCloud

Solving 3-D cloud kinematicCloud
Cloud: kinematicCloud
    Current number of parcels       = 143545
    Current mass in system          = 0.531278
    Linear momentum                 = (0 0 0)
   |Linear momentum|                = 0
    Linear kinetic energy           = 0
    Injector model1:
      - parcels added               = 226800
      - mass introduced             = 0.571889
    Parcel fate: system (number, mass)
      - escape                      = 83255, 0.0406116
    Parcel fate: patch Building (number, mass)
      - escape                      = 0, 0
      - stick                       = 12712904, 38.9585
    Parcel fate: patch Ground (number, mass)
      - escape                      = 0, 0
      - stick                       = 67206362, 266.319
    Parcel fate: patch Top (number, mass)
      - escape                      = 0, 0
      - stick                       = 0, 0
    Parcel fate: patch Domain (number, mass)
      - escape                      = 83255, 0.0406116
      - stick                       = 0, 0
    Rotational kinetic energy       = 0

ExecutionTime = 510.32 s  ClockTime = 513 s

The mesh is rather trivial as this is just a demo case, so this is just to be complete:

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1806                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : v1806
Arch   : "LSB;label=32;scalar=64"
Exec   : checkMesh
Date   : Aug 08 2018
Time   : 15:26:14
Host   : "acticom19"
PID    : 7698
I/O    : uncollated
Case   : /home/tom/Projecten/Amsterdam_Zuidoost/CFD/test_Rain
nProcs : 1
trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Time = 0

Mesh stats
    points:           10736
    faces:            29175
    internal faces:   26325
    cells:            9250
    faces per cell:   6
    boundary patches: 4
    point zones:      0
    face zones:       0
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     9250
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    Building            125      136      ok (non-closed singly connected)  
    Domain              1500     1600     ok (non-closed singly connected)  
    Top                 625      676      ok (non-closed singly connected)  
    Ground              600      660      ok (non-closed singly connected)  

Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    CellZone            Cells        Points        BoundingBox
    air                  9250         10736        (-2.5 -2.5 0) (2.5 2.5 3)

Checking geometry...
    Overall domain bounding box (-2.5 -2.5 0) (2.5 2.5 3)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-3.98329e-16 1.17073e-16 1.14413e-15) OK.
    Max cell openness = 2.60209e-16 OK.
    Max aspect ratio = 1.04037 OK.
    Minimum face area = 0.0383851. Maximum face area = 0.0416151.  Face area magnitudes OK.
    Min volume = 0.00782842. Max volume = 0.00817158.  Total volume = 74.  Cell volumes OK.
    Mesh non-orthogonality Max: 1.93496 average: 0.0355807
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.0207819 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

So bottom line: Is the above as expected, or is this a bug?

Regards,
Tom

[tomf]

Hi all,

Just an update on the issue. I could not fix the problem using OpenFOAM version 1806. Using the escaped particles did work for the solution of the engineering question.

Lately I have had a different project with particles that could stick to walls and I solved that with OpenFOAM v6. There the behavior was as expected. I did not check how version 1812 would behave.

Cheers,
Tom