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-   -   Heat transfer coefficient in CFX code (http://www.cfd-online.com/Forums/cfx/25930-heat-transfer-coefficient-cfx-code.html)

Halim June 12, 2008 04:45

Heat transfer coefficient in CFX code
 
Does any one know how to calculate the overall (not local) heat transfer coefficient (or Nusselt number) in CFX code?

Halim

hsr June 25, 2008 02:24

Re: Heat transfer coefficient in CFX code
 
Easiest way would be areaAve(Heat Transfer Coefficient)@<boundary>. It will give you an area weighted average of the variable

samanpnh February 7, 2013 18:56

aveage nusselt number monitoring as a function of time
 
1 Attachment(s)
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

ghorrocks February 7, 2013 19:54

Send your variable nuave to a monitor point, then you can see it as the transient simulation progresses on solver manager.

samanpnh February 8, 2013 06:33

1 Attachment(s)
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?

samanpnh February 8, 2013 06:42

1 Attachment(s)
this pic is better

ghorrocks February 8, 2013 07:00

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.

samanpnh February 8, 2013 08:36

What do you mean? Please tell me the exact code

also D1 or D2?

samanpnh February 8, 2013 11:50

What do you mean? Please tell me the exact code

also D1 or D2?

please help me:mad:

ghorrocks February 9, 2013 06:10

Replace nuL= (Wall Heat Flux *shoa*2[m])/(75 [K]*Thermal Conductivity )

with

nuL = areaAve(Wall Heat Flux)@Wall * shoa ..... * areaAve(k)@Wall

samanpnh February 9, 2013 07:26

Thank you very very very much. Error is cleared :eek::eek::eek::D:D:D

samanpnh February 9, 2013 08:57

What do you think about D1 or D2؟؟؟

ghorrocks February 10, 2013 05:20

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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