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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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particle size and geometric constraint of channel

Posted Jan 29, 2013, 10:25 a.m. EST Charged Particle Tracing, Microfluidics, Particle Tracing for Fluid Flow Version 4.3, Version 4.3a, Version 4.4 5 Replies

Chao Zhao
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Hi,

I designed a microfluidic channel with gaps at 10 um. Of course, particles with diameter at 1 um can go through this gap, but particles with diameter of 15 um still can go through this gap, which is not possible. How can I add geometric constraint besides the different forces for different sized particles?

Thank you.
5 Replies Last Post May 31, 2015, 8:52 p.m. EDT
Steve Kranz
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Posted: 1 decade ago Jan 29, 2013, 2:36 p.m. EST
You need to be more specific. What physics are you using? Are you in 2D or 3D? How are you simulating the particles. If you upload your .mph file it can help others get a better idea of what you're trying to do.
You need to be more specific. What physics are you using? Are you in 2D or 3D? How are you simulating the particles. If you upload your .mph file it can help others get a better idea of what you're trying to do.
Guangyu Liu
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Posted: 1 decade ago Mar 12, 2013, 11:14 a.m. EDT
Hi,
I met the same problem. I built a simple 2D model with laminar flow. The channel width is 1 micro meter. But the particle with 5 micro meter diameter can go through it.
Hi, I met the same problem. I built a simple 2D model with laminar flow. The channel width is 1 micro meter. But the particle with 5 micro meter diameter can go through it.

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Oak Yannapol
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Posted: 9 years ago Jan 21, 2015, 1:24 a.m. EST
Hi,

I have a similar problem as you. Why the large particle can go through smaller channel size ?
I did 3D geometry, Physics: particle tracing

I have changed the particle size, but particle size in the animation is same.
Hi, I have a similar problem as you. Why the large particle can go through smaller channel size ? I did 3D geometry, Physics: particle tracing I have changed the particle size, but particle size in the animation is same.
Walter Frei COMSOL Employee

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Posted: 9 years ago Feb 12, 2015, 2:29 p.m. EST
Hello All,

Keep in mind that the Particle Tracing for Fluid Flow assumes that the particle diameters are negligible compared to the other dimensions in your model. Of course, if the particle is larger than the channel, we know it won't go through the channel and the analysis is moot. Particles which are a significant fraction of, but still smaller than, the channel width can be treated with a Moving Mesh interface.
Hello All, Keep in mind that the Particle Tracing for Fluid Flow assumes that the particle diameters are negligible compared to the other dimensions in your model. Of course, if the particle is larger than the channel, we know it won't go through the channel and the analysis is moot. Particles which are a significant fraction of, but still smaller than, the channel width can be treated with a Moving Mesh interface.
Tianhang Bai
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Posted: 9 years ago May 31, 2015, 8:52 p.m. EDT

Hello All,

Keep in mind that the Particle Tracing for Fluid Flow assumes that the particle diameters are negligible compared to the other dimensions in your model. Of course, if the particle is larger than the channel, we know it won't go through the channel and the analysis is moot. Particles which are a significant fraction of, but still smaller than, the channel width can be treated with a Moving Mesh interface.


Hi Walter,

I tried to use Moving Mesh and it worked with a single particle. However, when I introduced another one, once the particle hit the wall of flow channel, or the two particles were about to collide with each other, it stopped running. Would you please give me some advice to solve that? Thanks a lot.

Regards,
tianhang
[QUOTE] Hello All, Keep in mind that the Particle Tracing for Fluid Flow assumes that the particle diameters are negligible compared to the other dimensions in your model. Of course, if the particle is larger than the channel, we know it won't go through the channel and the analysis is moot. Particles which are a significant fraction of, but still smaller than, the channel width can be treated with a Moving Mesh interface. [/QUOTE] Hi Walter, I tried to use Moving Mesh and it worked with a single particle. However, when I introduced another one, once the particle hit the wall of flow channel, or the two particles were about to collide with each other, it stopped running. Would you please give me some advice to solve that? Thanks a lot. Regards, tianhang

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