The governing equations of flow for

conservation of mass and momentum are given in equations below

📷📷📷

This udf is makes to add source terms for plunging motion

You have also to change the inlet profile to be consistent with the term source

/*************** FUNCTION FOR DEFINING SOURCE TERM*****************/

DEFINE_SOURCE(source_ymom,c,t,dS,eqn)

{

real source;

real y, yd, ydd;

real time = CURRENT_TIME;

real dens = C_R(c,t);

real xc[ND_ND];

C_CENTROID(xc,c,t); /*xy position of the cell*/

plungemotion(time,&y,&yd,&ydd);

source = -dens*ydd;

dS[eqn] = 0.0;

return source;

}

/******FUNCTION FOR DEFINING Y-VELOCITY AT VELOCITY INLET**********/

DEFINE_PROFILE(bc_v,thread,position)

{

face_t f;

real y, yd, ydd;

real time = CURRENT_TIME;

real xf[ND_ND];

plungemotion(time,&y,&yd,&ydd);

begin_f_loop(f,thread)

{

F_CENTROID(xf,f,thread);

F_PROFILE(f,thread,position) = -yd;

}

end_f_loop(f,thread)

}

/******* FUNCTION FOR DEFINING X-VELOCITY AT VELOCITY INLET ********/

DEFINE_PROFILE(bc_u,thread,position)

{

face_t f;

real time = CURRENT_TIME;

real xf[ND_ND];

begin_f_loop(f,thread)

{

F_CENTROID(xf,f,thread);

F_PROFILE(f,thread,position) = uinf; //free flow velocity//

}

end_f_loop(f,thread)

}