[andrea.pasquali]

Hi,
Is there in OF a code to calculate the frontal area "Aref" (for example the car frontal area) to calculate Cx and Cz using "forceCoeffs" function?

Thanks,
Andrea

[andrea.pasquali]

Hello,
I found "liftDrag" application for OF1.4.
I try to compile it on my OF 1.6.x without success...
Does any version exist for OF1.6 or 1.6.x ?
Does this application calculate the frontal area "Aref" ?

Thanks for any help!

Andrea

[louisgag]

Hi Andrea,

I am also looking for a way to easily calculate the frontal area of a complex 3D body. So far, it seems the only way to do it would be to sum the (area vectors dot the normal vector) on a whole physical surface and ignore negative values (to avoid having a zero total area!).

The code involved would look something like

mesh.Sf().boundaryField()

but I don't have time to do it at the moment.
and a loop like

forAllConstIter(labelHashSet, patchSet_, iter)

I'm just inspriring myself from the forces code....

Best regards,

-Louis

[louisgag]

I have looked into it some more and here's the exact command that will give you the frontal area (in x-direction)...

Info << "***********" << ( sumMag(Sfb[patchi].component(vector::X))/2 ) << "***************" << endl;

I'll get back with an actualy utility for this if I find the time to make one,


-Louis

EDIT: that formula only works if the part has no concavity (ie: holes inside) because this would count areas that should not be counted...

[bjornthe]

in the meantime, just do like this:
http://www.discretizer.org/node/20

Björn

[louisgag]

thanks for this very useful link. Just a note, if your shape contains some concavities you need to select cells through (or actually skip the extract selection step) and then divide the final result by two.

Cheers,

-Louis

[naveen]

hi louisgag,

Total area can be calculated using the liftdrag utility in OpenFOAM 1.4.1 by running liftDrag and put the same area at the end of controlDict of OpenFOAM 1.6....

Regards,

Naveen

[louisgag]

Thanks Naveen.