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Turbulence and Laminar model for empty narrow chan

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Old   October 4, 2004, 04:04
Default Turbulence and Laminar model for empty narrow chan
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KKLAU
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To CFD experts,

i am simulating the flow of a fluid in a narrow channel. I am sure this narrow channel will generate laminar flow since it is empty and Re < 1000. However, when i tried to simulate under laminar /turbulence(k-e) model, it gives different answer in term of velocity distribution for both models. May i know what makes this different ?

Thank you..

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Old   October 4, 2004, 07:49
Default Re: Turbulence and Laminar model for empty narrow
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John Luo
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Normal k-e turbulence inherently assumes that the Reynolds number is high and the flow is fully turbulent. That is, it can't simulate either laminar flow or transition. If you switch k-e on numerically, then it will generate turbulent viscosity and thereby additional diffusion, leading to a different solution from laminar one. There are low-reynolds number version of k-e which may performance better.
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Old   October 4, 2004, 22:51
Default How can i set k-e model for low Re??
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KKLAU
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To fluent experts:

How can i set k-e model for low Reynolds number? Is it same with the k-e RNG model????

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KKLAU
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Old   October 5, 2004, 02:35
Default Re: How can i set k-e model for low Re??
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SAM
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USE ENHANCED WALL TREATMENT OPTION
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Old   October 5, 2004, 04:11
Default Re: How can i set k-e model for low Re??
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SAM
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Enhanced wall treatment use to resolve viscous sub layaer so u have to be care ful for y plus values in ur calculation

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Old   October 18, 2004, 17:36
Default Re: How can i set k-e model for low Re??
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SAM
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now i have found something new

to use the ke with low Re number use this command

/define/models/viscous/turbulence-expert> low-re-ke Enable the low-Re k-epsilon turbulence model? [no] yes

this will help u i hope

regards

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