Fluid force in UDF
 

Hi, I am doing the external flow around the cylinder free oscillating in y-direction, a system the cylinder in fluid flow attached with spring and damper.

I had used SDOF function in Fluent and obtained some results.

But in the function for prop[SDOF_LOAD_F_Y], i just included elastic force, I also want to integrate fluid force into the equation. Anybody know how to include fluid force into UDF.

Thanks

DEFINE_SDOF_PROPERTIES(stage, prop,dt, time, dtime)
{
Thread *t;
Domain *d = Get_Domain(1);
real cg;
real vel;
real mass = 1.443;
real wn = 0.183;
real z = 0.0072;
real k = mass*wn*wn;
real c = 2*mass*wn*z;

int j;

prop[SDOF_MASS] = 1.443;
prop[SDOF_ZERO_TRANS_X] = TRUE;
prop[SDOF_ZERO_TRANS_Z] = TRUE;

prop[SDOF_ZERO_ROT_X] = TRUE;
prop[SDOF_ZERO_ROT_Y] = TRUE;
prop[SDOF_ZERO_ROT_Z] = TRUE;

cg = DT_CG(dt)[1];
vel = DT_VEL_CG(dt)[1];

prop[SDOF_LOAD_F_Y] = - k*cg - vel*c; /*function to update force into fluent*/

}