I have a solar chimney that air move in channel with natural.convection.i have source term on absorber valume that heat air.and now i want to calculate nusselt number for finding indepence mesh.how can calculate?
Heat transfer coefficient is a measurement of fictitious resistance to heat transfer at the wall. So, if the source term for natural convection is not incorporated in the wall, then probably Nusselt number has no meaning.For mesh independence test, mesh size near the wall could be made finer to check the Nusselt number which is readily available in FLUENT.
For simulating natural convection using volumetric source term, probably defining Rayleigh number as a custom function makes more sense.
@subhasish mitra: thanks for answer.but i dint know how can calculate nusselt number.can you help me?
Once you have simulated the case in Ansys Fluent,
To view the result for Nusselt Number :
(In Post Processor tab)Results--Graphics--Contours---Wall Fluxes---Surface Nusselt Number---Display
@smonath rangrej: i want to find average of nusselt number then in contour i cant.
Create Iso-Surface (plane section) at which you want to monitor the Average Nusselt Number Value.
Then Go to:
(In Post Processor tab)Results--Plots--XY Plot--Y Axis Function--Nusselt Number--Display
You can also monitor the Average Nusselt Number while simulation is running by crating Surface monitors.
I hope this helps.
Nu=hd/k or h=q/(Twall-Tmean) you can do it with CFD post. or try with Fluent report/ surface integral/ wall fluxes / Nusselt number surface
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