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Power flowing through a surface

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Old   October 19, 2009, 11:35
Default Power flowing through a surface
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How can I report the total power flowing through a surface that fluid passes through? I was thinking either a surface integral of velocity^3 or the sum of velocity^3 for the entire surface. Either way, Fluent's report only allows velocity^1; how can I use higher powers of velocity?
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Old   October 19, 2009, 12:07
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You can create Custom Field Function and a plane/ surface monitor, which will be reporting the Area-Weighted Average value of the CFF.
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Old   October 21, 2009, 14:05
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Could you expand on that Luke?
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Old   October 21, 2009, 15:34
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Hi.

In Fluent go to Define -> Custom Field Functions...

Here You can define desired functions.

Then go to Solve -> Monitors and create a monitor which will be reporting the area-weighted average(report type) of custom field function (field variable) you've created. In the Surfaces window select surface through which fluid flows.

Regards

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Old   October 27, 2009, 14:53
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Okay, so I defined a function called power-flux as density*axial velocity^3, solved, and did a surface integral to find it. Here's the problem: the power flowing in is correct, but the outflowing power (unverifiable) is larger than the input power. It's a simple 2d axisymmetric wind turbine modeled as just a pressure jump in the middle (actuator disk model). I've reversed the pressure drop and it's still a perpetual motion machine

Last edited by audrich; October 27, 2009 at 15:48.
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Old   October 28, 2009, 14:08
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Okay, need a fresh set of eyes here...my simulation is still showing higher power out than power in, can someone check to see any problems? The links show my mesh and fluent journal (simple shrouded turbine 2D). The only thing I can think of is regardless of the direction and sign of the pressure drop across the fan, it still says its a power addition rather than subtraction, which doesn't make sense. Help would be appreciated!

http://rapidshare.com/files/299187699/fluxwork.jou.html

http://rapidshare.com/files/29918519...esign.msh.html
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Old   February 22, 2010, 22:56
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This isnt really helping us out now audrich..
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