# Simulation CFD

#### wall film coefficient in natural convection

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12/19/2017 10:21 AM

Hi,

since we know that the LOCAL  film coefficient (h) for a fluid flowing over a constant temp. plate.

can be Obtained from the similarity solution at ɳ= 0. and the average value of h is the integration of the local value of

h along the plate length.

can we consider the value of wall film coefficient that we get from wall calculator in cfd as the average value of h also?

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#### Re: wall film coefficient in natural convection

12/19/2017 2:53 PM

I am sure you are right! The wall calculator will integrate local values over the surface of the wall.

You will have to explain a bit more about what you mean by a similarity solution as I haven't heard of that (always keen to learn though).

David Short
Technical Support Specialist, Simulation
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#### Re: wall film coefficient in natural convection

12/19/2017 5:05 PM

sounds nice... in this case, no need to worry about driving Nusselt number or h relations...magic

the similarty solution is an exact solution for the conversation equation in case of heat convection

the idea is to represent the conversation equation by one variable instead of velocity components orders

to get an ordinary differential equation instead of PDE. we need also to defend the boundary conditions in

term of similarity variables.

I'm  watching  this online course these days, you can also:

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