Learning Forum

[scabo]

Hi-I am using randomize injection option to inject DPM particles from the inlet of a pipe. Different particle tracks are going in different directions in an unsteady sim. How can i find out the initial injection location of particular particle track on the inlet so that I can detect which initial injection location is causing what deflection? I have exported particle tracks into CFDPost as Fluent does not show tracks for unsteady simulation but cannot get the initial position of each track. thanks.

[Rob]

You'll need to interrogate the .out file (manually) so determine what goes where, or if you know the parcel ID that's gone wherever you should be able to find it's first reported position. 

[scabo]

Hi-by the .out file do you mean the particle sampling file?

[Rob]

Yes. 

[scabo]

But I want to visualise the particle tracks. It is doable in CFDPost but not in Fluent. But you cannot export the position variable in CFDPost. So the only option is to track the sampling file I guess.

[Rob]

A transient particle track is a series of points in Fluent. A steady particle track in Fluent is a line showing it's trajectory. CFD Post takes the data from Fluent so why would you export position from CFD Post when it's an input? 

[scabo]

I mean when i export the particle history data to CFDPost and import as .xml then I can see tracks (continous lines) for unsteady simulation in CFDPost. But in Fluent you cannot see those similar tracks when you select particle tracks; instead you see particle positions. So CFDPost and Fluent show different things for the same input.

[Rob]

Are you sure about that?  https://ansyshelp.ansys.com/public/account/Secured?returnurl=/Views/Secured/corp/v252/en/flu_ug/flu_ug_sec_particle_history_export.html

[scabo]

Hi-yes i am sure. I have attached the CFDPost image which shows the unsteady particle track but you cannot see this in Fluent. I can also play a video showing the tracks developing in time. You can see particle position only in Fluent. Does these tracks of individual particles or parcels?

[Rob]

It'll be parcels. 

[scabo]

Okay just to say that I can only visualise the particle tracks/trajectories in CFDPost (after export) but cannot see the particle position or distribution. I think this is a drawback of the export.

[Rob]

I'm confused. If you've written the position out of Fluent, why would you need it in CFD Post? What distribution? 

[scabo]

Hi-I can export all the variables except the position variables from Fluent to CFDPost in the particle history file. I wanted to measure the x,y,z positions of the particle tracks in CFDPost because we cannot visualise the tracks in Fluent.

[scabo]

Hi-I am trying to create a 2D plane in the 3D pipe and do sample>plane>injection and press start. But when i submit the job to HPC it is not writing anything in the sample file. I wanted to visualise the particle position on the plane but it is not doing anything. What could be the issue?

[Rob]

Does Fluent try and save the sample file to the HPC disc or does it think the file is on your desktop? 

[scabo]

It creates the files in HPC but as the simulation progresses it does not write anything in the file althogh I can see particles crossing the surfaces in the results. I am selecting the injection and the surface and then selecting start and then submitting to HPC.

[Rob]

I can't remember if the start/stop options are remembered. You may need to reset on the HPC via the launch/run journal. 

[scabo]

Yea i have also tried writing the /report/dpm-sample/ injection-0 () interior-fluid () () no no command but it does not help.

[Rob]

Is that the correct command? I assume you've tested it locally? 

[scabo]

It creates the file but does not update it. I have not tested it locally, but let me check