UDF doubt
 

Hello everyone,

I am simulating the behaviour of the non-Newtonian fluid, Colgate on top of a vibrating membrane of a speaker. I have been working on a UDF to apply on a vibrating membrane, giving it a sinusoidal input velocity, i.e.,
v =v0* cos(pi*x/L)*sin(2*pi*f*t)

Where v0 is the maximum velocity achieved by the vibrating membrane and pi is already defined. f is the input frequency which I have obtained from previous experiments.

#include "udf.h"
#include "dynamesh_tools.h"
#define pi 3.1416
DEFINE_GEOM(plane,domain,dt,position)
{
position[1]=0.001;
}
DEFINE_GRID_MOTION(inlet_y_velocity,d,dt,time,dtim e)
{
Thread *t;
real y[ND_ND];
real x_c;
face_t f;
real v;
Node *w;
int n;
SET_DEFORMING_THREAD_FLAG(THREAD_TO(t));

begin_f_loop(f,t)
{
f_node_loop(f,t)
{
w = F_NODE(f,t,n);
if (NODE_X(v)>0 && NODE_X(v)<0.08 && NODE_Y(v)==0 && NODE_POS_NEED_UPDATE(v))
{
NODE_POS_UPDATED(v);
v=.2*cos((pi*x_c)/.08)*sin(2*pi*120*time);
}
end_f_loop(f,t)
}
}

I would like to know the correction for the errors in the code, as well as suggestions to improve the code.