Computation of kinetic energy of the flow
 

Hi foamers,
I am really puzzled about how tocompute the overall kinetic energy of the flow, i mean I(1/2*U^2)dV, where I is an integral over the given volume.
I understand that I have to sum over all subvolumes but I do not even know how to start . Please help me

volScalarField ke=0.5*(U&U);
dimensionedScalar ketotal = sum(ke*mesh.V());

Dear nimasam,
Thank you very much for your answer it was very useful.
Just a small comment,
It is better just to compute the Ek just by

dimensionedScalar ketotal = sum(0.5*(U&U)*mesh.V());

In this way you do not need to construct an additional volScalar field
which can save alot of memory
Yuri

Thinking about the issue once agin, the last change does not reduce the
memory consumption since U&U opration still consumpts the same amount of memory as if volScalarfield is defined explicitly. I would recommend another way , which is longer but allows you to save the memory:

forAll (mesh.C().internalField(), patchI)
{

Ekin_= Ekin_+0.5*
(sqr(U.internalField()[patchI].component(vector::X))+
sqr(U.internalField()[patchI].component(vector::Y))+
sqr(U.internalField()[patchI].component(vector::Z)))
*mesh.V()[patchI];
}
This is of course right for non-slip boundary conditions.
Yuri