找个动网格的算例，照着改呗。

类似这种：

#include"udf.h"

#define D 2e3

#define l 2e2

#define freq 1 

DEFINE_GRID_MOTION（grid_both , domain, dt , time, dtime)

{

face_t f;

Thread tf = DT_THREAD (dt);

int n;

Node *v;

real x;

real y;

..........................