Learning Forum

[fz.erraghroughi]

Hello! I am modeling particle deposition in bent pipes using the DPM model (unsteady tracking with one way coupling), so after running my simulation I need now to visualize the trapped particles at wall pipe, I have exported .dpm file via sampling report, but how to use this file in CFD post to visualize where exactly particles get trapped? I would be grateful if someone could give me some guidelines. Thanks in advance

[Rob]

We don't retain the particles when using trap: however if you write a dpm file it can be used to record the impact points. 

The alternatives are to look at the accretion model (in Fluent) or get very complicated and use moving mesh based on the former (not recommended unless you really know what you're doing and need that level of detail). 

As an aside, I'd suggest doing the post-processing in Fluent: it's much improved over previous versions and we're tending not to teach CFD Post for new Fluent users as of about R19.2  

[fz.erraghroughi]

Thank you, sir, for your reply!

I can't use the accretion model, unfortunately, since I use the one-way coupling. 

and for postprocessing in fluent, I have the possibility to display the particles that are still in the domain, not the particles that have deposited on the walls, thats why I use the sample report, it reports the fate of the particles and their coordinates in the boundary I selected. so how to use this file to visualize regions of trapped particles? Is it possible with Paraview software? 

 

[Rob]

Assuming it's a steady state model turn on coupled particles & display tracks: that'll give you accretion rates. Not sure about Paraview as it's not something I've used. 

[fz.erraghroughi]

Do you mean that after the end of my unsteady flow simulation and the unsteady tracking of particles I should change the flow to steady stat and turn on the coupling between phases to show the deposition locations?

because my flow is unsteady and also I use unsteady tracking for particles and no interaction with the continuous phase those changes will not affect the results?

another question: is reflect boundary condition is the same as trap BC when reflection coefficients are equal to zero?

[Rob]

If the flow is truly unsteady then my approach won't work. What's transient in the system?  No, reflect with zero reflection coefficients is likely to cause problems as the particles build up. Assuming the solver is OK you'll have a huge overhead holding all the particle data, read up on particle fates, specifically "incomplete" in the User's & Theory Guide. 

[fz.erraghroughi]

actually the unsteady thing in my simulation is the tracking (see the deposition buildup with time) so since I want to not include the effect of dispersed phase on the continuous phase I should work with the unsteady flow too thats way my system is transient.

[Rob]

OK, thanks for explaining.  With the DPM model you'll not see any build up with time, so steady with DPM will give an accretion rate (kg/m2/s). If you read the DPM theory you'll see particles don't occupy volume. 

[fz.erraghroughi]

ok, thanks for your replies sir.