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Old   January 16, 2014, 09:05
Default Solid particles not influenced by airflow
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Blauwe Kaas
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Hi,
I'm having trouble with particle tracking.
The solid particles are not influenced by the fluid they are in (Air at 25c). Even though they are Fully coupled with the air.
The particles only change direction when hitting a wall.
Has anyone seen this before?
Thanks!
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Old   January 16, 2014, 15:42
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Blauwe Kaas
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To clarify my problem:

The airflow which acts like it should:


And the particles, which just go straight ahead:
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Old   January 16, 2014, 18:08
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Glenn Horrocks
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Could be lots of things.

Are the material properties correct?
Is the interphase drag set correctly?
Is the particle integration time step set correctly?
Is the simulation converged?
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Old   January 18, 2014, 13:11
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Blauwe Kaas
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I check if they converged, but I was stupid enough to leave the maximum amount of iterations at 100.
After increasing the number, they still don't seem to converge.
Does this per se mean that the particles won't interact with the flow?
This is from the box posted above:


And the butterfly valve tutorial:
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Old   January 19, 2014, 05:54
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THis question is an FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

Don't pay too much attention to the convergence history of the tutorials. They show you how to set a simulation up, but they do not show you how to do an accurate simulation. THe results the tutorials give are not very accurate.

But don't worry about the convergence for now, you have a more fundamental problem if the particles travel in straight lines. The points I raise in my previous post are a starting point in what to check.
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