Heat transfer coefficient in CFX code

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 June 12, 2008, 04:45 Heat transfer coefficient in CFX code #1 Halim Guest   Posts: n/a Does any one know how to calculate the overall (not local) heat transfer coefficient (or Nusselt number) in CFX code? Halim

 June 25, 2008, 02:24 Re: Heat transfer coefficient in CFX code #2 hsr Guest   Posts: n/a Easiest way would be areaAve(Heat Transfer Coefficient)@. It will give you an area weighted average of the variable

February 7, 2013, 18:56
aveage nusselt number monitoring as a function of time
#3
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saman
Join Date: Jan 2013
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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
Attached Images
 1.jpg (34.8 KB, 17 views)

 February 7, 2013, 19:54 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,709 Rep Power: 98 Send your variable nuave to a monitor point, then you can see it as the transient simulation progresses on solver manager.

February 8, 2013, 06:33
#5
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saman
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I have another question. Is shown in the photo. Instead of (2 * shoa) D1 or D2 should I use?
Attached Images
 2.jpg (52.6 KB, 18 views)

February 8, 2013, 06:42
#6
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saman
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this pic is better
Attached Images
 2.jpg (91.2 KB, 14 views)

 February 8, 2013, 07:00 #7 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,709 Rep Power: 98 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.

 February 8, 2013, 08:36 #8 New Member   saman Join Date: Jan 2013 Posts: 9 Rep Power: 5 What do you mean? Please tell me the exact code also D1 or D2?

 February 8, 2013, 11:50 #9 New Member   saman Join Date: Jan 2013 Posts: 9 Rep Power: 5 What do you mean? Please tell me the exact code also D1 or D2? please help me

 February 9, 2013, 06:10 #10 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,709 Rep Power: 98 Replace nuL= (Wall Heat Flux *shoa*2[m])/(75 [K]*Thermal Conductivity ) with nuL = areaAve(Wall Heat Flux)@Wall * shoa ..... * areaAve(k)@Wall

 February 9, 2013, 07:26 #11 New Member   saman Join Date: Jan 2013 Posts: 9 Rep Power: 5 Thank you very very very much. Error is cleared

 February 9, 2013, 08:57 #12 New Member   saman Join Date: Jan 2013 Posts: 9 Rep Power: 5 What do you think about D1 or D2؟؟؟

 February 10, 2013, 05:20 #13 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,709 Rep Power: 98 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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