[Mike_star]

Hello everyone,

I am simulating the aerodynamic behavior of a 2D airfoil and trying to find the lift, drag and moment coefficients using forceCoeffs. I found a relevant code online as follows:
functions
{
forces
{
type forceCoeffs;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches
(
wing
);
pName p;
UName U;
rhoName rhoInf;
log true;
rhoInf 1;
CofR ( 0 0 0 );
liftDir ( 0.087 0.996 0 );
dragDir ( -0.996 0.087 0 );
pitchAxis ( 0 0 1 );
magUInf 75.00;
lRef 1;
Aref 1;
}
}

I had some questions about this code:
1- what is CofR (0 0 0) ? is this the origin of the coordinate system of the whole domain (global coordinate system)? or is it the center of mass of the airfoil !?
2- I know liftDir and dragDir are the direction of the lift and drag forces. How about pitchAxis ( 0 0 1 )? is it the direction of the pitch axis? or is it the position of the pitch axis (if this the position, should I use the global coordinate system)?
3- can anyone please explain lRef 1; and Aref 1; lines for me? what are these lines for? and what should be the value of them? can I leave them as 1?

Thank you all and really need your help!