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Heat transfer coefficient in CFX code

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Old   June 12, 2008, 04:45
Default Heat transfer coefficient in CFX code
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Halim
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Does any one know how to calculate the overall (not local) heat transfer coefficient (or Nusselt number) in CFX code?

Halim
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Old   June 25, 2008, 02:24
Default Re: Heat transfer coefficient in CFX code
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hsr
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Easiest way would be areaAve(Heat Transfer Coefficient)@<boundary>. It will give you an area weighted average of the variable
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Old   February 7, 2013, 18:56
Question aveage nusselt number monitoring as a function of time
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I wrote a code that gives average nusselt number in steady state as a scalar number for a cylinder in cross flow with Induced Vibrations
local nusselt
nuL= (Wall Heat Flux *shoa*2[m])/(75 [K]*Thermal Conductivity )
that 75 is Temperature difference
average nusselt number
nuave=areaAve(nuL)@Pipe1

I think it works for you

but I need a way that plot average nusselt number as a function of time like the follow picture
Please somebody help me
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Old   February 7, 2013, 19:54
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Send your variable nuave to a monitor point, then you can see it as the transient simulation progresses on solver manager.
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Old   February 8, 2013, 06:33
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I did exact the same thing, but it gives this error in follow picture. please help me

I have another question. Is shown in the photo. Instead of (2 * shoa) D1 or D2 should I use?
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Old   February 8, 2013, 06:42
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this pic is better
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Old   February 8, 2013, 07:00
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Looks like the areaAve function can only take CFX variables, not your CEL expression. In that case just do the averaging in the nuL equation.
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Old   February 8, 2013, 08:36
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What do you mean? Please tell me the exact code

also D1 or D2?
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Old   February 8, 2013, 11:50
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What do you mean? Please tell me the exact code

also D1 or D2?

please help me
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Old   February 9, 2013, 06:10
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Replace nuL= (Wall Heat Flux *shoa*2[m])/(75 [K]*Thermal Conductivity )

with

nuL = areaAve(Wall Heat Flux)@Wall * shoa ..... * areaAve(k)@Wall
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Old   February 9, 2013, 07:26
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Thank you very very very much. Error is cleared
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Old   February 9, 2013, 08:57
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What do you think about D1 or D2؟؟؟
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Old   February 10, 2013, 05:20
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If you are trying to match a publish result then they should define how they calculated Nu. There is no general rule, you can define it anyway which makes sense to that application.
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