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Heat flux through a boundary

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Hi guys

Ive been roughly following this tutorial to model a heat exchanger www.youtube.com/watch?v=7U5ue03K7gQ

Using different geometry and BC's

It uses the expression intop1(nitf.qwf_u) to calculate the total power exchange

Im having some trouble getting this to work in my model, I understand that intop1 means it is integrating nitf.qwf_u over the boundary but I just dont know what nitf.qwf_u means and what the equivalent in my model would be.

Any help is appreciated

Thanks

1 Reply Last Post 2 mag 2015, 04:18 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 10 years ago 2 mag 2015, 04:18 GMT-4
Hi

turn on the equation view and check the description of the variable, there are so many that I cannot tell you exactly what that one does, but I suspect that the last "u" could indicate its along the X direction, in which case, if your surface is not normal to the "x" direction your results is not the total flux but only one component. Normally the flux one integrate is the normal flux, hence the dot product of the surface normal and the flux variable components

--
Good luck
Ivar
Hi turn on the equation view and check the description of the variable, there are so many that I cannot tell you exactly what that one does, but I suspect that the last "u" could indicate its along the X direction, in which case, if your surface is not normal to the "x" direction your results is not the total flux but only one component. Normally the flux one integrate is the normal flux, hence the dot product of the surface normal and the flux variable components -- Good luck Ivar

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