Learning Forum

[Bill Hsu]

Hello everyone, I'm using the volume injection in the DPM, and I want to initialize the domain with uniformly distributed pariticle. My problem is that after I run the simulation and I try to check the particle residence time, the particles didn't show up. My injection start time is 0, and the stop time is 0.05, which is the same as my time step size (I want the particle inject only once) , the particle initial velocity is set as 0, I'm wonder if I do anything wrong? the following pictures are my screenshots of my simulation.

[Rob]

If you open the Particle Track panel, then change the size/display option can you see them? At 2.5microns the particles will follow the flow, and are also very small so may not be easily seen. 

[Bill Hsu]

 

Thanks for your suggestions, Rob! I’ve changed the particle residence time into the particle diameter, and the particles showed up in my model. However, after I ran my simulation (Numbers of timestep=5000, timestep size=0.05), the particles didn’t move. I already give a inlet air velocity with 2.5 m/s, and I don’t know why the particles didn’t move with flow (My assumption is one-way coupling). The following picture is the locations of 160 parcels, and the location is fixed no matter the time pass.

 

[Rob]

Odd. Can you ignore the animate tool and replot the particle tracks at a later time? In the File>Preferences find and turn on Titles. That adds a couple of lines of text at the bottom of the image which includes the solver time. 

If you plot a couple of contours of velocity on the model at a later time how does it look? Use isosurfaces/planes (both work, I just prefer the former) to show what's happening inside the domain. 

[Bill Hsu]

Thanks for your suggestion again!  I had exported the particle track data (variables: particle diameter, particle velocity ) from fluent and imported the data into the CFD post. however, when I set up the contour, there's no option for the DPM variables. I think the reason why the DPM variables didn't show up is because my assumption is one-way coupling?  But my case should be done in one-way coupling, is there any method to show the DPM varables without enable the "interaction with continous phase"? So far I know the DPM concentration can be plot by using UDF in one-way coupling, but I'm wondering for the particle diameter or particle velocity if there's any more efficient way to show them.

[Rob]

DPM data doesn't always transfer to CFD Post, I'd do all of the post processing in Fluent. We did recommend CFD Post for some versions, but that's reverted to Fluent as the post processing has been improved over the last few releases. 

[Bill Hsu]

Thanks for your suggestion, I'll do the post processing in Fluent.