[ACif95]

Hello everyone! I'm begginner on the field of UDFs and i am trying to program a cylindrical expansion. The problem is that i don't know how to save the initial coordinates for the mesh cells to add a displacement on each time step without taking into account the displacement of the latest time step. As i show in the next UDF, if i use NV_VS(N_COORD(v),=,N_COORD(v),'+','disp') it will accumulate the displacement of each time step and it will not move as i would like.

#include "udf.h"
#include "dynamesh_tools.h"

#define Dext 0.06
#define Dint 0.02
#define h 0.4

DEFINE_GRID_MOTION(case13d,domain,dt,time,dtime)
{
face_t f;
Thread *tf=DT_THREAD(dt);
int n;
Node *v;
real A[ND_ND];
real NV_VEC(axis);
real Mag;
real disp;
real z;
SET_DEFORMING_THREAD_FLAG(THREAD_T0(tf));
begin_f_loop(f,tf)
{
f_node_loop(f,tf,n)
{
F_AREA(A,f,tf);
Mag=NV_MAG(A);
A[0]=A[0]/Mag;
A[1]=A[1]/Mag;
A[2]=A[2]/Mag;
NV_D(axis,=,A[0],A[1],A[2]);
v=F_NODE(f,tf,n);
z=NODE_Z(v);
disp= Dext/10*sin(M_PI*(CURRENT_TIME-z/2))*sin(2*z/h*M_PI);
/*disp=D/100*sin(M_PI*(CURRENT_TIME));*/
if (NODE_POS_NEED_UPDATE(v))
{
NODE_POS_UPDATED(v);
NV_V_VS(NODE_COORD(v), =, NODE_COORD(v), +, axis,*,disp);
}
}

}
end_f_loop(f,tf);
}

Could anyone help me about this?

Regards