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-   -   Particle tracking problem with MRF (http://www.cfd-online.com/Forums/cfx/123757-particle-tracking-problem-mrf.html)

bioexplore September 20, 2013 05:47

Particle tracking problem with MRF
 
Hi all,

I have encountered the problem with particle tracking in a stirred tank simulation with the Multiple Reference Frame method, the setting of my model is like this:

Firstly, I use Freeze/Roter (MRF) to get the initial steady state velocity field in the stirred tank reactor,
Then, freeze the velocity field and inject the particles at one small boundary (inlet of the stirred tank), one way coupling (particles have no effect on the velcoity of liquid) of these particles was used, I aslo active the expert parameter of 'pt tracks in absolute frame', but the resulted trajectories of each particle showed that it discontinued at the interface between non-rotating zone and rotating zone.

Has any body met with this probem of particle tracking with MRF?

Any comments and suggestions is appreciated!

Jianye

ghorrocks September 20, 2013 06:17

FAQ:

http://www.cfd-online.com/Wiki/Ansys...f_reference.3F

bioexplore September 20, 2013 06:53

Thanks, Glenn!

I red that, but my problem is not the streamline but particle trajectory.
The trajectory disconnected across the station/rotating interface.

Jianye

ghorrocks September 20, 2013 07:48

Streamline or particle track, the effect is the same. The change in reference frame means tracks do not appear continuous.

bioexplore September 20, 2013 08:22

Glenn, can you make it more clear?

Quote:

To see continuous streamlines plot the variable "Velocity in stationary frame". This is referenced to the stationary frame regardless of whether the frame is rotating or not, so will be continuous. You might need to access this variable using the puzzlingly labelled "..." button
How can I find the "..." button? Does it in the cfx5post.exe GUI?

When I process the particle trakcing results, there is "Res PT for Particle" in the model tree, when I double clicked it, there was no options for selecting "Velocity in stn frame" in the setting panel of "Res PT for Particle".

I have toggle on the expert parameter of "'pt tracks in absolute frame'", that should be mean that the particle will follow the velocity in stationary fram, am I right?

And what does it mean by "To see continuous streamlines plot the variable "Velocity in stationary frame". "?

How did you do that? can you provide more details ? Thanks a lot!

ghorrocks September 20, 2013 08:27

The FAQ is referring to CFD-Post.

I am not aware of the "pt tracks in absolute frame" expert parameter but I presume it does what it says it does and those tracks should be continuous.

Plotting the variable "Velocity in stationary frame" is relevant to streamlines only. This option is not available for particle tracks.

bioexplore September 20, 2013 08:40

It is sure not continuous
 
See attached figure: the red arrow point the disconnectied trajectories

http://v2.freep.cn/3tb_1309202037424tus512293.png

ghorrocks September 21, 2013 06:18

I am not sure what is happening there. Have you checked your particle termination parameters?

bioexplore September 22, 2013 16:13

I have also checked with the termination parameters, but it did also not work!

Any other clues?


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