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Error in free convection

Posted May 17, 2013, 6:34 a.m. EDT Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 3.5a 2 Replies

Francesco Carelli
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I am trying to model a natural convection, creating a volume of air around the object i want to simulate.
I didn't have acceptable results, so I'm trying to realize larger volumes or to use alternative shapes for the volume.

But when I do it, and try to simulate i have the following error message that interrupts my simulation:

'Errror 6199
Attempt to evaluate square root of a negative number.
Function sqrt'

how could an enlargement of the geometric dimensions of the volume cause such problem?
2 Replies Last Post Jun 6, 2014, 12:01 p.m. EDT
Francesco Carelli
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Posted: 1 decade ago May 21, 2013, 4:53 a.m. EDT
no ideas?

it's really strange, i have always error with larger dimensions, and never when I return to the original ones... maybe with dimensions too large there is an overflow problem?
no ideas? it's really strange, i have always error with larger dimensions, and never when I return to the original ones... maybe with dimensions too large there is an overflow problem?
Fatu Viorel
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Posted: 1 decade ago Jun 6, 2014, 12:01 p.m. EDT
Hi,

If you are using material properties from library try to modify the presure at rho tab from 'p' to 'p+patm' where the 'patm' you define in constants as the atmospheric presure (101325 Pa).
Do that at both of the phisycs (HT and CFD) if you are using library materials at both modules




All the best,
Viorel
Hi, If you are using material properties from library try to modify the presure at rho tab from 'p' to 'p+patm' where the 'patm' you define in constants as the atmospheric presure (101325 Pa). Do that at both of the phisycs (HT and CFD) if you are using library materials at both modules All the best, Viorel

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