Heating efficiency through solid surface

kjetil · June 20, 2016, 02:26

Dear cfx people,

I am setting up a simple problem to find the heat transfer coefficient / heating efficiency through forced convection on a plain surface, versus using some means to disturb the boundary layer and generate near wall turbulence to aid increased heat transfer. What would be the best way to evaluate the heat flux on the opposite solid side of the plain surface? areaInt() of Wall Heat Flux may perhaps be a an option? (My original thought was to use the overall surface temperature.)

ghorrocks · June 20, 2016, 07:18

Are you looking for the steady state heat flux? If that is the case then there is no need to model the solid as the heat flux from the fluid = heat flux out the solid, so just model the fluid and save the hassle of modelling the solid.

And yes, areaInt(Wall Heat Flux)@... sounds like a good function for this - assuming you are applying a constant temperature boundary condition (or a convection BC).

kjetil · June 20, 2016, 07:36

Right. Yes, steady state heat flux is sufficient.

Another thing - heating is performed with a Variable Composition gas mix from a fixed circular inlet. Would you say it is possibly to calculate Heat Flux over this inlet as well similarly to the wall surface mentioned above? I am not quite sure how CFX would treat these two different type of patches, where one involves advection.

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June 20, 2016, 07:18		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,705 Rep Power: 143	Are you looking for the steady state heat flux? If that is the case then there is no need to model the solid as the heat flux from the fluid = heat flux out the solid, so just model the fluid and save the hassle of modelling the solid. And yes, areaInt(Wall Heat Flux)@... sounds like a good function for this - assuming you are applying a constant temperature boundary condition (or a convection BC).

June 20, 2016, 07:36		#3
kjetil Senior Member Join Date: Mar 2009 Location: Norway Posts: 137 Rep Power: 17	Right. Yes, steady state heat flux is sufficient. Another thing - heating is performed with a Variable Composition gas mix from a fixed circular inlet. Would you say it is possibly to calculate Heat Flux over this inlet as well similarly to the wall surface mentioned above? I am not quite sure how CFX would treat these two different type of patches, where one involves advection.