Nussult number or Heat transfer calculation

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  • Last Post 17 January 2019
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mdfaizan444 posted this 16 January 2019

How we can calculate the Nussult number or heat transfer coefficient when temperature is given as a boundary condition on the wavy wall?  

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raul.raghav posted this 16 January 2019

You would have to define it as an expression. See the following video for reference:

Rahul

mdfaizan444 posted this 17 January 2019

First thanks for the valuable reference. But i have a constant wall temperature not the constant heat flux and secondly how can i define mixed fluid temperature as Tm? Is ANSYS fluent already known that Tm is mixed fluid temperature or i have to define it somewhere?

raul.raghav posted this 17 January 2019

When a constant temperature is applied as the boundary condition at the walls, the heat transfer between the wall and a cell in the fluid domain is defined by:

q = h * (T_wall - T_ref)

where T_ref is the reference temperature you provide. You need to be careful providing the T_ref value, as that can result in the underestimation or overestimation of convective heat transfer coefficient (h) value. I'd highly recommend you to go through the following paper which compares the convective heat transfer coefficient obtained with T_ref value evaluated in different ways:

Determination of surface convective heat transfer coefficients by CFD

Rahul

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