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Old   September 17, 2016, 14:39
Default EEqn.H
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S Atkinson
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Hi All,

I have been trying to understand the EEqn.h using http://cfd.direct/openfoam/energy-equation/ and the file itself. From the file;

fvScalarMatrix EEqn
(
fvm::ddt(rho, he) + fvm::div(phi, he)
+ fvc::ddt(rho, K) + fvc::div(phi, K)
+ (
he.name() == "e"
? fvc::div
(
fvc::absolute(phi/fvc::interpolate(rho), U),
p,
"div(phiv,p)"
)
: -dpdt
)
- fvm::laplacian(turbulence->alphaEff(), he)
==
rho*(U&g)
+ radiation->Sh(thermo)
+ fvOptions(rho, he)
);

I fully understand the LHS and the process that is happening there from the website. I am a little confused why I, the Identity tensor gets swapped in it becomes U in equation 12.

Following this I want to know what rho*(U&g) is in physical terms. I understand that rho*g gives joules, which makes sense, but what is rho*U kg/m2.s.

Thanks,

satkinson
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Old   October 31, 2016, 02:00
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Bo Kong
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rho*gU is potential energy
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Old   October 31, 2016, 06:31
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S Atkinson
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Hi huangfei

Thanks for updating me on this.

Satkinson
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Old   October 31, 2016, 07:02
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Joachim Herb
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Quote:
Originally Posted by huangfei View Post
rho*gU is potential energy
I think this is the change of the potential energy (density). [J/s/m]
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