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Fire and smoke modelling

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paolofug87

Mechanical
Sep 29, 2017
1
Hi guys,

I'm wondering about model setup for simulating smoke, here some question:

1- My smoke is made up of CO CO2 and a scalar (soot), which is the typical value for UDS diffusivity? I found a CFX tutorial that says 1e-5 m^2/s with a soot density of 2000 kg/m3 but fluent asks for a value in kg/(m*s). I need to multiply for that density or just the density of the mixture (approximately the air density at that temperature)?

2- What is a the best setup for DO radiation model, and typical values for gas absorption coefficient: the material mentioned above says that the following formula can be used:
0.01 + 1.5*density*soot mass fraction/(smoke density * smoke diameter) [1/m]
and provides values for:
smoke density = 2000 kg/m3
smoke diameter 1e-6
By the way, the soot mass fraction is the one I can check when plotting the scalar contour?

Thank you in advance

Paolo
 
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