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how to model dimensionless channel?

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Old   March 25, 2013, 06:59
Default how to model dimensionless channel?
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shahrbanoo
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Hello…
I have an article and this article evaluated a channel with ribs on it’s walls. I want to model this channel In Gambit and work on it, but all of the data in the article is dimensionless. What should I do? Can I guess?
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Old   March 25, 2013, 08:27
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I would think that if they mentioned a Reynolds number you could back out a dimension and go from there.
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Old   March 25, 2013, 09:10
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it's natuaral convection and Rayleigh number is used, but I don't have temperature difference to calculate channel width!
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Old   March 25, 2013, 09:14
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Just pick a length and go. You should have something like l/L =.9.. pick a l and get a L
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Old   March 25, 2013, 09:59
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Hi, I think the characteristic length (L) usually taken to non-dimensionalize the equations for channel flow is the half-width of the channel. Then you have to non-dimensionalize all the geometrical features with this characteristic length (ribs, etc.).

You will have to solve the equations in dimensionless form. Given the characteristic length, the Rayleigh number and the fluid properties you can impose the temperature difference by setting the upper wall temperature to 0 and the temperature of the lower wall to T_{bottom}=\frac{Ra_L}{L^3} \cdot \frac{\nu \cdot \alpha}{g \cdot \beta}.

Wait for other replies.

Cheers,
Michujo.
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