Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
How to Plot particle locations from a Particle Tracing for Fluid Flow experiment
Posted 2016年8月3日 GMT-4 16:03 Charged Particle Tracing, Computational Fluid Dynamics (CFD), Particle Tracing for Fluid Flow 3 Replies
Please login with a confirmed email address before reporting spam
Hello,
I'm using the Laminar Flow and Particle Tracing for Fluid Flow to model the mixing of blood and acridine orange in my cartridges. I can't figure out how to just get a 3D plot of the locations of the particles after the simulation.
Also, if there are better options to use for the Physics, please let me know. I am trying to evaluate the quality of the mixing with different designs.
Best,
Dan
I'm using the Laminar Flow and Particle Tracing for Fluid Flow to model the mixing of blood and acridine orange in my cartridges. I can't figure out how to just get a 3D plot of the locations of the particles after the simulation.
Also, if there are better options to use for the Physics, please let me know. I am trying to evaluate the quality of the mixing with different designs.
Best,
Dan
3 Replies Last Post 2016年11月14日 GMT-5 10:06
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
Hello, I've made a bit more progress in this area. By watching the "How to Simulate Particle Tracing in a Laminar Static Mixer" and mirroring those setting with my setup, I am now able to get a 3D figure of the particle locations.However, the figure shows all of the particles gathered at the inlet, and none beyond it. I can't figure out why.
Perhaps of note, under "Particle Tracing for Fluid Flow" -> "Initial position" -> "Density Proportional to:" if I put "spf.U" in that field, (as recommended by the video), when I perform the time-dependent particle tracking study, I get the following message: "The following feature has encountered a problem: Zero or negative particle density. --Feature: Time-Dependent Solver 1 (sol2/t1)." So instead I put 1 in this field, allowing it to run without error but as previously mentioned, the particles don't seem to move.
Any help would be greatly appreciated.
Perhaps of note, under "Particle Tracing for Fluid Flow" -> "Initial position" -> "Density Proportional to:" if I put "spf.U" in that field, (as recommended by the video), when I perform the time-dependent particle tracking study, I get the following message: "The following feature has encountered a problem: Zero or negative particle density. --Feature: Time-Dependent Solver 1 (sol2/t1)." So instead I put 1 in this field, allowing it to run without error but as previously mentioned, the particles don't seem to move.
Any help would be greatly appreciated.
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
Hello, I've made a bit more progress in this area. By watching the "How to Simulate Particle Tracing in a Laminar Static Mixer" and mirroring those setting with my setup, I am now able to get a 3D figure of the particle locations.However, the figure shows all of the particles gathered at the inlet, and none beyond it. I can't figure out why.
Perhaps of note, under "Particle Tracing for Fluid Flow" -> "Initial position" -> "Density Proportional to:" if I put "spf.U" in that field, (as recommended by the video), when I perform the time-dependent particle tracking study, I get the following message: "The following feature has encountered a problem: Zero or negative particle density. --Feature: Time-Dependent Solver 1 (sol2/t1)." So instead I put 1 in this field, allowing it to run without error but as previously mentioned, the particles don't seem to move.
Any help would be greatly appreciated.
Hi Dan,
I have met the same problem with you. "Zero or negative particle density"
Have you solved it ? Would you please give some instructions to me?
Thank you in advance.
Best Regards,
Bill
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
Hi Dan, Bill:
There are a couple of reasons why the error message "Zero or negative particle density" might occur, but if you're trying to make the initial density of particles at the Inlet proportional to the velocity magnitude spf.U, the most common mistake is to forget to set the "Values of variables not solved for" in the settings for the Time Dependent study. The "Values of variables not solved for" should be "User Controlled" and the "Study" should be a valid stationary or time-dependent study that has already been computed, in which the Inlet velocity is nonzero.
See the attached screenshot, taken from the tutorial "Particle Trajectories in a Laminar Static Mixer" [www.comsol.com/model/particle-trajectories-in-a-laminar-static-mixer-10644].
If you've double-checked the "Values of variables not solved for" and found that everything matches the setup in the tutorial, but you still get the error "Zero or negative particle density", then I'd recommend submitting your model to COMSOL support for further assistance.
Best Regards,
Chris
There are a couple of reasons why the error message "Zero or negative particle density" might occur, but if you're trying to make the initial density of particles at the Inlet proportional to the velocity magnitude spf.U, the most common mistake is to forget to set the "Values of variables not solved for" in the settings for the Time Dependent study. The "Values of variables not solved for" should be "User Controlled" and the "Study" should be a valid stationary or time-dependent study that has already been computed, in which the Inlet velocity is nonzero.
See the attached screenshot, taken from the tutorial "Particle Trajectories in a Laminar Static Mixer" [www.comsol.com/model/particle-trajectories-in-a-laminar-static-mixer-10644].
If you've double-checked the "Values of variables not solved for" and found that everything matches the setup in the tutorial, but you still get the error "Zero or negative particle density", then I'd recommend submitting your model to COMSOL support for further assistance.
Best Regards,
Chris
Attachments: