How to deal with PIC particles being "still not cool"

MFiX
1

Hi,
Running fine fractions with PIC often yields this “still not cool” message, which I understand means that parcels/particles are removed from the system. This is also visible in the inventory plot below. I have so far tried to reduce the timestep and statistical weight, without any luck. The message still appears when trying with uniform and larger particle sizes (within the original PSD).

There is one post on the same topic here on the forum, but I couldn’t find what else to try, as I interpret “fluid timestep” as the main timestep found in the “Run” section. Any other advice?

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This inventory curve is based on a stepped inlet velocity increase, thereby the accelerated removal of particles.

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2

Hi @kjetilbmoe As indicated in "Still not cool" Message this is a developer debug message that should have been cleaned up before release, since it is not helpful for our users and is possibly confusing (“cool” can relate to temperature but that’s not what it means here :smiling_face_with_sunglasses:) I will do this for the 25.4 release, replacing it with a more appropriate message like “Particle removed”, but this does not help the underlying problem of why the particles are being removed.

You are correct that “fluid time step” is the same thng as the main timestep (“Dt”). I’m not sure what else there is to try here. I’ll check with the developer of this code and see if I can find any further suggestions.

3

I think this could be a bad mesh issue. I am looking into it.

1 Like
5

Thanks, indeed it seems to be mesh related, too high mesh tolerances.