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Old   June 3, 2005, 07:47
Default turbulent diffusivity
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confused
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why do we assume a constant turbulent diffusivity for all species in a reacting flow?

surely hydrogen is diffused more than, say, oxygen by tubulence. i.e. due to the fact it is lighter.

why dont we use a different turbulent Schmidt number for each species?

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Old   June 3, 2005, 10:56
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ram
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i dont know
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Old   June 3, 2005, 11:10
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agg
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This is because turbulent diffusivity is not a preperty of a particular fluid, but that of the turbulent flow.
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Old   June 3, 2005, 17:58
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confused
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hi agg,

ok. but still in reality would you not expect lighter species to be transported more than heavier ones by turbulence?

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Old   June 4, 2005, 16:29
Default Re: turbulent diffusivity
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agg
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That is true. Hence for example in LES dynamic models are used to account for the differences (if my understanding is correct). A constant is an approximation (and has worked) to simplify the model.
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