Surface Enlargement Factor of a ribbed Surface

D2Net15 · November 23, 2017, 08:10

Hello everyone,

i want to simulate a simplified geometry with the same Heat Flux of a ribbed Surface and my question is how do i do this?

For clarifications:
I have a ribbed plate and a known Heat flux of X W/m^2.
Now i want to simulate a flat plate and want to get the same Heat Flux of X W/m^2.

I already know that i can achieve this through rough Walls and to determine the roughness height and constant iterativly, but it is kind of bulky.

Thank you for your help.

ghorrocks · November 24, 2017, 05:13

If you know the heat flux of the boundary then just use a heat flux boundary condition.

D2Net15 · November 24, 2017, 05:30

I think I have to be more clear on this side.

Lets assume we have a plate with a source in it´s inside and i want to get the same heat flux at the fluid boundary with a ribbed and non-ribbed plate. I could get a factor for the flat plate to achieve this.

Now, i want to adapt this procedure to a more complex geometry. For this geometry the heat flux at the boundary is not known but the mentioned factor. Furthermore, the ribs are too many and complex to model/mesh them, that´s the reason why i want to get this factor.

Btw. it is essential, that i have two bodies - the plate and the fluid.

ghorrocks · November 25, 2017, 05:31

In this case I recommend you look into heat transfer textbooks for thermal resistance. You can determine the thermal resistance of the flat plate and the ribbed plate and use the thermal resistance as the heat flux at the boundary.

This is assuming thermal resistance is an appropriate model for what you are trying to do.

November 23, 2017, 08:10	Surface Enlargement Factor of a ribbed Surface	#1
D2Net15 New Member Join Date: Oct 2014 Posts: 8 Rep Power: 11	Hello everyone, i want to simulate a simplified geometry with the same Heat Flux of a ribbed Surface and my question is how do i do this? For clarifications: I have a ribbed plate and a known Heat flux of X W/m^2. Now i want to simulate a flat plate and want to get the same Heat Flux of X W/m^2. I already know that i can achieve this through rough Walls and to determine the roughness height and constant iterativly, but it is kind of bulky. Thank you for your help.

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November 24, 2017, 05:13		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	If you know the heat flux of the boundary then just use a heat flux boundary condition.

November 24, 2017, 05:30		#3
D2Net15 New Member Join Date: Oct 2014 Posts: 8 Rep Power: 11	I think I have to be more clear on this side. Lets assume we have a plate with a source in it´s inside and i want to get the same heat flux at the fluid boundary with a ribbed and non-ribbed plate. I could get a factor for the flat plate to achieve this. Now, i want to adapt this procedure to a more complex geometry. For this geometry the heat flux at the boundary is not known but the mentioned factor. Furthermore, the ribs are too many and complex to model/mesh them, that´s the reason why i want to get this factor. Btw. it is essential, that i have two bodies - the plate and the fluid.

November 25, 2017, 05:31		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	In this case I recommend you look into heat transfer textbooks for thermal resistance. You can determine the thermal resistance of the flat plate and the ribbed plate and use the thermal resistance as the heat flux at the boundary. This is assuming thermal resistance is an appropriate model for what you are trying to do.