| FlavioC |
May 11, 2019 21:20 |
Reflect Condition dpm
Hello to everyone. I am studying the reflect condition for inert particles, I use the code that appears in the udf fluent manual
Code:
DEFINE_DPM_BC(bc_reflect,p,t,f,f_normal,dim)
{
real alpha;
/* angle of particle path with face normal */
real vn=0.;
real nor_coeff = 1.;
real tan_coeff = 0.3;
real normal[3];
int i, idim = dim;
real NV_VEC(x);
#if RP_2D
/* dim is always 2 in 2D compilation. Need special treatment for 2d axisymmetric and swirl flows */
if (rp_axi_swirl)
{
real R = sqrt(p->state.pos[1]*p->state.pos[1] + p->state.pos[2]*p->state.pos[2]);
if (R > 1.e-20)
{
idim = 3;
normal[0] = f_normal[0];
normal[1] = (f_normal[1]*p->state.pos[1])/R;
normal[2] = (f_normal[1]*p->state.pos[2])/R;
}
else
{
for (i=0; i<idim; i++)
normal[i] = f_normal[i];
}
}
else
#endif
for (i=0; i<idim; i++)
normal[i] = f_normal[i];
if(p->type==DPM_TYPE_INERT)
{
alpha = M_PI/2. - acos(MAX(-1.,MIN(1.,NV_DOT(normal,p->state.V)/ MAX(NV_MAG(p->state.V),DPM_SMALL))));
if ((NNULLP(t)) && (THREAD_TYPE(t) == THREAD_F_WALL))
F_CENTROID(x,f,t);
/* calculate the normal component, rescale its magnitude by the coefficient of restitution and subtract the change */
/* Compute normal velocity. */
for(i=0; i<idim; i++)
vn += p->state.V[i]*normal[i];
/* Subtract off normal velocity. */
for(i=0; i<idim; i++)
p->state.V[i] -= vn*normal[i];
/* Apply tangential coefficient of restitution. */
for(i=0; i<idim; i++)
p->state.V[i] *= tan_coeff;
/* Add reflected normal velocity. */
for(i=0; i<idim; i++)
p->state.V[i] -= nor_coeff*vn*normal[i];
/* Store new velocity in state0 of particle */
for(i=0; i<idim; i++)
p->state0.V[i] = p->state.V[i];
return PATH_ACTIVE;
}
return PATH_ABORT;
}
But I change the tangent coefficient value setting it to one since the collision should be elastic. Then, I compare the particles trajectories using the UDF and the boundary condition type :reflect. The trajectories are so different. Can someone please explain it to me? |
