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April 17, 2002, 13:25 |
Smoke visibility
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#1 |
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Dear Fluent users,
Has anyone got experience in modelling a smokesource in Fluent and setting up a value for visibility. We are allso interested in the relation between smokeproduction and heat output. Thanks in advance. |
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April 18, 2002, 09:34 |
Re: Smoke visibility
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#2 |
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stricly speaking, smoke is a combination of carbon particulates (1-20 micron dia) and gases ... i usually model smoke as the products of the chemical equation describing the combustion and so i usually model a mixture of air and "smoke" with an air mass sink to account for oxygen consumption and a smoke mass source plus the energy source.
to report, in the way of post-processing, for the visibility in the domain of interest... visibility post-processing is related to the mass concentration of the smoke and several fluent customers do this regularly ... here is some background information on smoke production and visibility: http://fire.nist.gov/bfrlpubs/fire95/PDF/f95126.pdf http://fire.nist.gov/bfrlpubs/fire00/PDF/f00164.pdf basically visibility can be defined as the distance at which the contrast of an object relative to its backgrounds drops below a certain fraction. the visibility S, [m] depends on the smoke mass concentration C, [g/m3] and on the specific extinction coefficient Km, [m2/g] which depends on the material being burned for a light emitting sign S = 8 / (Km*C) for a light reflecting sign S = 3 / (Km*C) this is simple to create a post-processing variable in fluent because the smoke concentration density is readily available |
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December 5, 2020, 07:01 |
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#3 | |
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Mahesh
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Quote:
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December 5, 2020, 10:21 |
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December 5, 2020, 11:01 |
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#5 |
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Mahesh
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Sry for my mistake. I meant to say that the visibility is becoming infinite where the smoke concentration is zero and I could not plot the visibility as the post processing shows error. Kindly help me how to plot in such case.
Thanks in advance |
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December 5, 2020, 15:05 |
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#6 |
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Make it finite but a big value in such case. I have no idea how you implemented this, because you did not give any info, so I can't tell you how to change your implementation.
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