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Old   November 19, 2013, 00:43
Question Particle tracking problem
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hello everyone, I am doing a simulation of particle tracking in the air flow. The flow is in a 90 degree bent pipe, with a horizontal inlet and a upright outlet. The particle is released with the inlet flow at the inlet.

My problem is that, when I track the particle, the particle is terminate at the horizontal part of the pipe, with no particle at the bent and upright part of the pipe. Do you know why and be so kind to tell me how should I do?

The particle is modeled by "particle transport solid" and the coupling model is set to be fully coupled.

I would appreciate you much for any clue you suggest.

Thank you very much,
BalanceChen
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Old   November 19, 2013, 05:04
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Glenn Horrocks
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Have you checked your particle termination parameters? They might be terminating your particle early. Alternately, have you checked that your particle will get around the corner? If it hits the wall (and you have no resititution to make it bounce off) it will terminate the track.
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Old   November 20, 2013, 01:16
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Thank you very much, ghorrocks. I am sorry to bother you again, my wall interaction option is set to be "equation dependent", and the restitution coefficient is 1.0 for perpendicular coeff. and 1.0 for parallel coeff. Is there any problem in the settings?

Thank you again,
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Old   November 20, 2013, 06:17
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1.0 for coeff of restitution means particles will bounce off the walls, they will not terminate.

So if your tracks are terminating early you have two things to look at:
1) The other particle termination criteria (time, integration steps etc)
2) Particle track accuracy - a particle track will be captured more accurately on a fine mesh than a coarse on. So the normal mesh sensitivity study should look at particle track termination. But like any good CFD user, you have already done a mesh sensitivity study and confirmed your mesh is fine enough, haven't you?
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Old   November 20, 2013, 06:59
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Thank you very much, ghorrocks. I i ignore the default value of 10 for the maxium tracking distance, but the problem of mine has a very large length with about 50m, and. It should work if i modify this value.

thank you again,
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Old   February 6, 2014, 07:29
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sorry for reviving 6 months old post...but i face a very similar problem. All my particle tracks terminate at the horizontal part. my horizontal part has a free slip wall boundary BC. res and parallel coeffic - 1 , checked all termination parameters. my mesh is fine. so i now have no idea where the problem is

pls help me with it. and thanks a lot in advance!
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