I am simulating natural convection in a square cavity with side wall at constant temperature and bottom and top adiabatic. How can I calculate average Nu using ANSYS/FLUENT or at different locations in cavity? Thanks.
you should use the definition of the Nusselt number. you may take a look at the following article (sections 3.2 and 3.3) introducing this procedure:
M. Mirzaei, M. Dehghan, Investigation of flow and heat transfer of nanofluid in microchannel with variable property approach, Heat Mass Transfer 49 (2013) 1803-1811.
you can also find the full text on my page (in Researchgate.net).
I assume you have a steady-state situation with one hot and one cold sidewall. Then: How about simply performing surface integration/averaging to obtain the average heat flux and use Newton's law of cooling (since walltemperatures are known) in order toobtain the heat transfer coefficient? The length scale in Nu may need some attention, though.
@Erling, Thanks for your comments. I am actually trying to simulate well known problem of natural convection in a square cavity. Isotherms and streamlines looks similar to what is expected but Nu calculated using ANSYS/FLUENT at hot wall with Reports\area weighted average\wall fluxes\Surface Nu is far away from standard values. That's reason i am looking for a good suggestion to solve this problem. I would really welcome any suggestion that you had experience with such calculation.
- Badges
- Science topic