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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 The information provided may be out of date.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 29.01.2013, 10:25 GMT-5 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 31.05.2015, 20:52 GMT-4
Steve Kranz
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Posted: 1 decade ago 29.01.2013, 14:36 GMT-5
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 12.03.2013, 11:14 GMT-4
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: 1 decade ago 21.01.2015, 01:24 GMT-5
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: 1 decade ago 12.02.2015, 14:29 GMT-5
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: 1 decade ago 31.05.2015, 20:52 GMT-4

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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