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correct diffusivity for turbulent flow model

Posted 23 feb 2012, 10:37 GMT-5 Fluid & Heat, Computational Fluid Dynamics (CFD), Chemical Reaction Engineering Version 4.2a 0 Replies

Robert Low
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I'm modelling dispersion of a gas jet into an air flow through a duct and am using the turbulent single-phase flow physics with the k-epsilon flow model, together with "transport of diluted species" physics. I have Fick diffusion coefficient for the gas in air but wondered if I should modify the apparent diffusivity in the "transport of diluted species" physics to be the sum of Fick diffusivity and the local turbulent diffusivity?

I can calculate the local turbulent diffusivity as Dturb = nitf.muT/nitf.rho ie ratio of local turbulent viscosity to gas density, which is consistent with the flow model, but then that made me think about whether this is double-counting, since the bulk flow pattern is already being calculated by the flow field.

Any advice gratefully received - this is my first big venture into CFD type studies, most of my COMSOL use to date has been for chemical reactor modelling.
0 Replies Last Post 23 feb 2012, 10:37 GMT-5
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