August 8, 2023 at 9:42 amraju.chowdhurySubscriber
I want to set slip boundary conditions at the gas-liquid interface in my DPM model. Can you suggest to me how I can do that?
Also, my job is terminating and getting the following message while running it in HPC.
" iter continuity x-velocity y-velocity z-velocity time/iter
!29253 solution is converged
29253 7.8724e-04 1.0817e-06 1.9034e-06 1.1926e-06 0:00:07 28
Advancing DPM injections ....
number tracked = 90, escaped = 1
Open existing project file for writing: bubble_particle.flprj
Error at host:
failed to open file
===============Message from the Cortex Process================================
Compute processes interrupted. Processing can be resumed.
failed to open file
Error Object: #f
This is only happening when dpm model is on. Without dpm model, the job is running nicely. I believe I need to add few commands in my journal script. But I do not have any idea what I need to add when the dpm model is ON.
Any useful suggestion from anyone will be highly appreciated.
August 8, 2023 at 1:37 pmRobAnsys Employee
The DPM model doesn't see the free surface as such, it sees the cell fluid properties. So, unless you want to start some (very complex) UDF coding your particles will behave exactly as the flow in that cell forces them too.
The flpj file is a way for Fluent to keep data files together for a transient run. Can you check disc/file access permissions as it should work fine.
August 8, 2023 at 4:00 pmraju.chowdhurySubscriber
How can I check disc/file access permissions?
August 8, 2023 at 4:02 pmRobAnsys Employee
Rename the flpj file and try to run again. Where are you saving the files to? Ie your own PC, random location on a network etc.
August 10, 2023 at 10:35 amraju.chowdhurySubscriber
I followed your instruction but still not working. Please note that my other simulations are working fine. Only this simulation where I am using dpm model, shows that error.
August 10, 2023 at 10:49 amRobAnsys Employee
What else are you triggering at the 10th iteration/timestep? DPM on it's own shouldn't cause problems, and the error points towards something disc related.
August 14, 2023 at 8:40 amraju.chowdhurySubscriber
Thanks, Rob. The previous problem of crushing the job in HPC has been identified and resolved.
I have the following queries:
(1) I am injecting particles from a single point. I expect to release the particle in one line (the blue line marked in the below image). Why the particles are distributed throughout the entire domain over time? How can I fix the issue?
(2) Is there any way to implement when a particle reach (or touch) the gas-liquid interface, the particle will either trap or slip?
August 14, 2023 at 10:05 amRobAnsys Employee
As I've not seen the injection, and don't know how the flow is behaving I can't comment on why you're not getting a single stream of particles.
If you want to trap particles at the free surface you'd need to write a UDF to terminate particles at they hit the free surface or (easier to set up but potentially more computationally expensive) look at DPM-to-VOF.
August 14, 2023 at 3:33 pmraju.chowdhurySubscriber
It is just a bubble rising due to buoyancy in water.
August 14, 2023 at 3:37 pmRobAnsys Employee
And what are the DPM particles?
August 14, 2023 at 3:39 pmraju.chowdhurySubscriber
Particles with a density 2500 kg/m3.
August 14, 2023 at 4:00 pmRobAnsys Employee
August 14, 2023 at 4:01 pmraju.chowdhurySubscriber
August 14, 2023 at 4:04 pmRobAnsys Employee
Maybe add some images of the flow field (vectors), contours of phase etc. Tea leaves only get me so far....
August 14, 2023 at 6:27 pm
August 15, 2023 at 10:13 amRobAnsys Employee
What's the settling velocity for the particles? Flow isn't all "down" and depending on 3d effects you could have enough disturbance in the flow to explain the above. What is the particle velocity?
August 15, 2023 at 11:49 amraju.chowdhurySubscriber
August 15, 2023 at 12:51 pmRobAnsys Employee
And if you plot the vertical velocity component on the plane, how much is going up sufficiently quickly to cause particles to rise? Clipping the range is often a useful tool to see what's going on.
August 21, 2023 at 7:50 amraju.chowdhurySubscriber
I have found the water velocity is higher at some positions compared to the particle's velocity. That could be one reason to float the particles instead of going down.
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