Dear RG Members
my question is regarding the natural convection heat transfer inside enclosure filled with nanofluid. the enclosure shape is square. the two vertical walls are kept at an isothermal different temperatures while the two horizontal walls are considered adiabatic. The results present in term of streamlines and isotherms contours which they can be evaluated from CFD Commercial code ANSYS FLUENT. also, the heat transfer rate (Nusselt Number value) is very important in the discussion of the results for the natural convection heat transfer. i would like to ask how to :
1. plot local Nusselt number along the heated wall?
2. determine the average Nusselt number?
By the way how can i added the nanofluid thermophysical properties? i have an idea like i added them by replace the propoerties of air by nanofluid properties and solved separately and then compare between the Nusselt number with and without nanofluid addition to explain how nanofluid enhances the heat transfer rate?
Sincerely,
1- The local Nusselt number plot:
*choose plot * XYplot * Wall fluxes (Y axis function ) *Surface Nusselt Number.* Chosse the wall where you want to show Nusselt number then *Plot.
2- To calculate the average Nusselt number use the formulation
Nu = hL/k.
Where h is Surface heat transfer coefficient obtained again from Contours of Wall fluxes. ( surface integral --> wall flux (Area-weighted average) -> heat transfer coefficient )
Or directly.
*Report---> Surface integrals-->Area-weighted average --> Wall fluxes--> Surface Nusselt surface--> Compute (Area-weighted average).
Good Luck
Replacing air to the nanofluid is questionable. Try multi-phase rather than doing like that
1- The local Nusselt number plot:
*choose plot * XYplot * Wall fluxes (Y axis function ) *Surface Nusselt Number.* Chosse the wall where you want to show Nusselt number then *Plot.
2- To calculate the average Nusselt number use the formulation
Nu = hL/k.
Where h is Surface heat transfer coefficient obtained again from Contours of Wall fluxes. ( surface integral --> wall flux (Area-weighted average) -> heat transfer coefficient )
Or directly.
*Report---> Surface integrals-->Area-weighted average --> Wall fluxes--> Surface Nusselt surface--> Compute (Area-weighted average).
Good Luck
Dear Manigandan Sekar
thanks for your opinion
but do you have published paper regarding this topic? i used Mixiture Model for simulation two-phase flow and i think it is not valid for nanofluid due to small diameters (micro level)
Dear Abdelkadir Belhadj
thank you very much for your explanation it is really helpful
Dear Sir.
I recommend the answer of Abdelkadir Belhadj and there is another way to get it from FLUENT program it self but its not easy as ANSYS CFD POST steps
Good luck
Dear All,
I am agreed with Mr. Amr Kaood the results are varying for Re 10000, Re 15000 I'm working on a very simple case of pipe flow with water as fluid in a pipe of dimension 2 m long and 0.02 m & 0.025 m in outer diameter.
But for Re 20000 the results are very precise bu dittus boelter the value is 117.06 and I'm getting from ansys is 116 , can anyone help me out for Re 10000 & 15000
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