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Laminar Flow and Heat Transfer

Posted Mar 23, 2018, 3:47 a.m. EDT Computational Fluid Dynamics (CFD) Version 5.2 1 Reply

Ankit
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Hello!

I am trying to model 3D laminar flow with heat transfer in a rectangular channel. I have coupled both the physics through the Multiphysics node. When I set the reference pressure pref as zero, I get the error message "Division by zero". As my model is not open to atmosphere, I do not want to keep the pref as 1[atm] (default value). Kindly provide your suggestions in this regard.

Thanks in advance.

1 Reply Last Post Mar 23, 2018, 8:02 a.m. EDT
Erik Bornhöft COMSOL Employee

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Posted: 7 years ago Mar 23, 2018, 8:02 a.m. EDT

Dear Ankit,

do you maybe use a pressure dependent gas density? You might get a zero density then. Set the reference pressure according to your conditions. If it is close to vacuum you might want to consider molecular flow instead of laminar flow.

See also: https://www.comsol.com/blogs/how-to-assign-fluid-pressure-in-cfd-simulations/

And: https://www.comsol.com/blogs/what-is-molecular-flow/

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Best regards,
Erik

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Erik Bornhöft
COMSOL Germany
Dear Ankit, do you maybe use a pressure dependent gas density? You might get a zero density then. Set the reference pressure according to your conditions. If it is close to vacuum you might want to consider molecular flow instead of laminar flow. See also: https://www.comsol.com/blogs/how-to-assign-fluid-pressure-in-cfd-simulations/ And: https://www.comsol.com/blogs/what-is-molecular-flow/

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