Learning Forum

[MohAgha1]

Dear All;

Is there a special treatment for DEM when using symmetry BCs in the 3D geometries or for the 2D geometries?

I got this warning when I was tracking parcels of 2 mm diameter in 2cmx2cm 2D cells 

"

number tracked = 115488, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 57744, incomplete_parallel = 0

number tracked = 115488, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 57744, incomplete_parallel = 0

 

WARNING: 50.0000% of the total discrete phase mass was not tracked for the expected residence time:

0.001 s less on a mass-weighted average (which is 20.0000% of their total age or 100.0000% of the last time step).

You may be able to reduce this discrepancy by changing the tracking parameters, that is,

increasing the maximum number of time steps used to compute a single particle trajectory.

 

Done. 

"

N.P. the dem time-step (2e-5) is less than the collision time step (2e-4)

 

Regards;

Mohamed

[DrAmine]

Should check your tracking parameters which influence the calculation of the trajectory. Use smaller particle time step size might help too. 

[MohAgha1]

I tried the same case with all the same parameters for a 3D case "wall BCs" and it was working fine, but just I changed to the symmetry BCs, I got this warning and the transient solution become very slow!!

Is there any issue relating this change? any other parameters?

Regards;

Mohamed

[DrAmine]

Is it now 2D, 3D or what? Please be more precise in your description.  Moreover I have large doubts how the DEM model will behave at a symmetry boundary. Try free slip wall.

[MohAgha1]

Alright,

I tried three cases

1- 3D Geometry with walls BCs

2- 3D Geometry with symmetry BCs

3- 2D Geometry 

 on the first case, the program runs without warnings or problems, while I got the mentioned warning in the second and the third cases

Regards;

Mohamed

[DrAmine]

DEM is not compatible with axis-symmetric cases. Moreover I have large doubts about beavior at symmetry boundaries. You can check free slip walls. 

[MohAgha1]

"DEM is not compatible with axis-symmetric cases."

Is this include 2D wall-bounded cases as well?

Moreover I have large doubts about beavior at symmetry boundaries. You can check free slip walls. 

In case of free-slip wall it works fine, but it gives warning with symmetry BC

 

Mohamed

[DrAmine]

Both are equivalent for your case so use the one working for you.

[MohAgha1]

I got the following terminating error when I starting calculation of the 2D case

 

Build Time: Apr  9 2018 14:07:42 

Executable Path: CPROGRA~1/ANSYSI~1/ANSYS Student/v191/fluent/ntbin/win64/fluent.exe

 

---

ID    Hostname         Core  O.S.         PID    Vendor                     

---

n0*   DESKTOP-xxxxxx  1/4  Windows-x64  10016  Intel(R) Core(TM) i7-3537U 

host  DESKTOP-xxxxxx       Windows-x64  2652   Intel(R) Core(TM) i7-3537U 

 

MPI Option Selected: ibmmpi

Selected system interconnect: default

---

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Initialization"))

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Initialization"))

(cx-gui-do cx-activate-item "NavigationPane*List_Tree1")

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Initialization"))

(cx-gui-do cx-activate-item "Solution Initialization*Table1*ButtonBox8*PushButton1(Initialize)")

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Run Calculation"))

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Run Calculation"))

(cx-gui-do cx-activate-item "NavigationPane*List_Tree1")

(cx-gui-do cx-set-list-tree-selections "NavigationPane*List_Tree1" (list "Solution|Run Calculation"))

(cx-gui-do cx-activate-item "Run Calculation*Table1*PushButton22(Calculate)")

Registering Udf, ("C:UsersxxxxxFLUENTxxxx_filesdp0FFF-4FluentFFF-4.1Fluentmixing.c")

 

Writing Settings file "C:UsersxxxxxFLUENTxxxx_filesdp0FFF-4FluentFFF-4.1.set"...

writing rp variables ... Done.

writing domain variables ... Done.

writing fb:043 (type fluid) (mixture) ... Done.

writing fb:023 (type fluid) (mixture) ... Done.

writing fb (type fluid) (mixture) ... Done.

writing interior-fb:027 (type interior) (mixture) ... Done.

writing interior-fb:031 (type interior) (mixture) ... Done.

writing interior-fb:004:035 (type interior) (mixture) ... Done.

writing wall-fb:039 (type wall) (mixture) ... Done.

writing interior-fb:004 (type interior) (mixture) ... Done.

writing interior-fb:011 (type interior) (mixture) ... Done.

writing inlet:015 (type velocity-inlet) (mixture) ... Done.

writing wall-fb:019 (type wall) (mixture) ... Done.

writing interior-fb (type interior) (mixture) ... Done.

writing inlet (type velocity-inlet) (mixture) ... Done.

writing outlet (type pressure-outlet) (mixture) ... Done.

writing wall-fb (type wall) (mixture) ... Done.

writing interior-fb:027 (type interior) (solid-2) ... Done.

writing interior-fb:027 (type interior) (solid-1) ... Done.

writing interior-fb:027 (type interior) (gas) ... Done.

writing interior-fb:031 (type interior) (solid-2) ... Done.

writing interior-fb:031 (type interior) (solid-1) ... Done.

writing interior-fb:031 (type interior) (gas) ... Done.

writing interior-fb:004:035 (type interior) (solid-2) ... Done.

writing interior-fb:004:035 (type interior) (solid-1) ... Done.

writing interior-fb:004:035 (type interior) (gas) ... Done.

writing wall-fb:039 (type wall) (solid-2) ... Done.

writing wall-fb:039 (type wall) (solid-1) ... Done.

writing wall-fb:039 (type wall) (gas) ... Done.

writing fb:043 (type fluid) (solid-2) ... Done.

writing fb:043 (type fluid) (solid-1) ... Done.

writing fb:043 (type fluid) (gas) ... Done.

writing interior-fb:004 (type interior) (solid-2) ... Done.

writing interior-fb:004 (type interior) (solid-1) ... Done.

writing interior-fb:004 (type interior) (gas) ... Done.

writing interior-fb:011 (type interior) (solid-2) ... Done.

writing interior-fb:011 (type interior) (solid-1) ... Done.

writing interior-fb:011 (type interior) (gas) ... Done.

writing inlet:015 (type velocity-inlet) (solid-2) ... Done.

writing inlet:015 (type velocity-inlet) (solid-1) ... Done.

writing inlet:015 (type velocity-inlet) (gas) ... Done.

writing wall-fb:019 (type wall) (solid-2) ... Done.

writing wall-fb:019 (type wall) (solid-1) ... Done.

writing wall-fb:019 (type wall) (gas) ... Done.

writing fb:023 (type fluid) (solid-2) ... Done.

writing fb:023 (type fluid) (solid-1) ... Done.

writing fb:023 (type fluid) (gas) ... Done.

writing wall-fb (type wall) (gas) ... Done.

writing outlet (type pressure-outlet) (gas) ... Done.

writing inlet (type velocity-inlet) (gas) ... Done.

writing interior-fb (type interior) (gas) ... Done.

writing fb (type fluid) (gas) ... Done.

writing wall-fb (type wall) (solid-1) ... Done.

writing outlet (type pressure-outlet) (solid-1) ... Done.

writing inlet (type velocity-inlet) (solid-1) ... Done.

writing interior-fb (type interior) (solid-1) ... Done.

writing fb (type fluid) (solid-1) ... Done.

writing wall-fb (type wall) (solid-2) ... Done.

writing outlet (type pressure-outlet) (solid-2) ... Done.

writing inlet (type velocity-inlet) (solid-2) ... Done.

writing interior-fb (type interior) (solid-2) ... Done.

writing fb (type fluid) (solid-2) ... Done.

writing zones map name-id ... Done.

 

Host receiving summary from compute node zero.

Writing "| gzip -2cf > FFF-4.1-1.cas.gz"...

Writing temporary file C:\Users\xxxxxxxxx\AppData\Local\Temp\flntgz-26522 ...

     560 quadrilateral cells, zone  2, binary.

     120 quadrilateral cells, zone 43, binary.

     120 quadrilateral cells, zone 23, binary.

    1069 2D interior faces, zone  1, binary.

     217 2D interior faces, zone 31, binary.

       8 2D interior faces, zone 27, binary.

     217 2D interior faces, zone 11, binary.

       8 2D interior faces, zone  4, binary.

      15 2D interior faces, zone 35, binary.

       8 2D velocity-inlet faces, zone  5, binary.

       8 2D velocity-inlet faces, zone 15, binary.

      16 2D pressure-outlet faces, zone  6, binary.

      70 2D wall faces, zone  7, binary.

      15 2D wall faces, zone 39, binary.

      15 2D wall faces, zone 19, binary.

     867 nodes, binary.

     867 node flags, binary.

Done.

 

Writing "| gzip -2cf > FFF-4.1-1-00000.dat.gz"...

Writing temporary file C:\Users\xxxxxxx\AppData\Local\Temp\flntgz-26523 ...

Done.

 

MI: 0.000000

MPI Application rank 0 exited before MPI_Finalize() with status -1073741676

 

[MohAgha1]

I set the particle diameter in the point properties panel to the physical particle diameter = 7e-4 , 

while the parcel diameter in the parcel panel was set to 1e-5 which corresponds to the 2d parcel size in the 2d domain as calculated in the fluent theory guide 

Am I true in this set-up?

 

Regards;

Mohamed

[DrAmine]

The 2D diameter is an output not an input

[MohAgha1]

So, the diameter in the following point panel is the physical particle or the parcel diameter?

 

 

 

[DrAmine]

Physical particle diameter