[federicabi]

Hi everyone!
I'm stuck on a problem, because I'm new in programming in openFOAM. I need to compile a new restraint similar to linearSpring, so I took a look at the .H and .c files of linearSpring restraint and I need to modify the restraintForce term with a time varying force composed like this: (Fx,0,Fx*tan(alpha)).
Fx is the sum of Fx pressure and Fx viscous and it needs to be extract each time step from the forces.dat file. alpha is the angle between the initial position of the x-axis of the system and the new position, I think it can be extract from the motion.orientation() tensor each time step. The problem is that I don't know how to extract these data to put them into the linearSpring library.

I tried to modify the library like below


void Foam::sixDoFRigidBodyMotionRestraints::linearSprin g::restrain
(
const sixDoFRigidBodyMotion& motion,
vector& restraintPosition,
vector& restraintForce,
vector& restraintMoment
) const
{
restraintPosition = motion.transform(refAttachmentPt_);

vector r = restraintPosition - anchor_;

scalar magR = mag(r);
r /= (magR + VSMALL);

vector v = motion.velocity(restraintPosition);

restraintForce = vector(Fx,0,Fx*tan(alpha))

restraintMoment = vector::zero;

if (motion.report())
{
Info<< " attachmentPt - anchor " << r*magR
<< " spring length " << magR
<< " force " << restraintForce
<< endl;
}
}

Now I need to build a new function in this dictionary to extract Fx and alpha.
Anyone knows how can I do that?
Your help would be very appreciated.

Best regards

Federica