# how to plot local nusselt number vs X/d (length) in fluent 18.1

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January 9, 2018, 07:14
how to plot local nusselt number vs X/d (length) in fluent 18.1
#1
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waqar hazoor
Join Date: Oct 2017
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hi all
can any body help me how to plot the graph shown in attached picture.

i am using ANSYS fluent 18.1

flat heated plate

circular air jet strikes the plat solution is converged temperature values i get are fine.

but dont know how to draw local nusselt number vs length at interface of solid and fluid

thanks.
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 January 10, 2018, 07:54 #2 Member   Daniel Edebro Join Date: Feb 2016 Location: Gothenburg Posts: 39 Rep Power: 8 My two cents 1. Create a user line from r = 0 outward radially 2. Calculate local HTC using T_amb, T_wall and wall heat flux 3. Calculate local Nusselt using Nu = HTC(r)*L/k, where k is the conductivity of the fluid. I am guessing that length scale L is the diameter of the jet but that should be definied in your article

 February 1, 2018, 13:51 #3 New Member   waqar hazoor Join Date: Oct 2017 Posts: 24 Rep Power: 6 dear can you kindly guide me how to calculate the Nusstle number at a stagnation point in transition case, i want to plot Nusstle number vs Re to validate my case with others Far likes this.

March 27, 2018, 09:00
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Quote:
 Originally Posted by DEd My two cents 1. Create a user line from r = 0 outward radially 2. Calculate local HTC using T_amb, T_wall and wall heat flux 3. Calculate local Nusselt using Nu = HTC(r)*L/k, where k is the conductivity of the fluid. I am guessing that length scale L is the diameter of the jet but that should be definied in your article

Dear Daniel,

can we use "Plot-->WallFluxes--->Surface Nusselt Number" to get local Nu, instead?

March 27, 2018, 18:29
#5
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Lucky
Join Date: Apr 2011
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Quote:
 Originally Posted by vidyadhar Dear Daniel, can we use "Plot-->WallFluxes--->Surface Nusselt Number" to get local Nu, instead? Thanks in advance!
Yes but you need to remember to set the reference temperature and length the reference values pane. If you have a variable thermal conductivity, I'm not sure how Fluent calculates the Nusselt number for those cases. Presumably it would use the the thermal conductivity of the wall adjacent cell but one would have to check and make sure. If your properties are constant, then no worries.