Hi all,

i have a cylinder in 2d with moving wall in the left wall (i am using a UDF), the cylinder is filling in the half with metal liquid, there is a velocity inlet in the left of the top wall, and pressure outlet in the right of the top wall, i'd like to move the wall to push liquid's metal to move and to escape from the gate(pressure outlet), i have compiled my UDF(containing the equation of the velocity of the moving wall) successfuly, my Libudf was opened...but the moving wall was not moving.......i don't know where is the problem, what should i define in the boundary conditions? Or i shoule define a UDF for the DynamicMesh...

#include "udf.h"

static real v_prev = 0.0;

static real A = 0.00009;

static real f = 1;

DEFINE_CG_MOTION(piston,dt,vel,omega,time,dtime)

{

/* reset velocities */

NV_S(vel, =, 0.0);

NV_S(omega, =, 0.0);

if (!Data_Valid_P())

return;

/* equation of velocity */

v_prev = 2*3.142*A*f*sin(2*3.142*f*time+3.142/2);

/* set x-component of velocity */

vel[0] = v_prev;

}

Regards for all

Your UDF seems fine (especially if it compiled and opened!), you need to tell Fluent what wall to move and in which direction.

(This is assuming you haven't already): Go to your dynamic mesh zones, and make the wall that you want to move a moving zone, and select your UDF there, and set the direction you want it to move (x-direction = 1, y-direction = 0, z-direction = 0).

Save & Apply, then re-run the simulation (or mesh motion) to check if its moving properly.

but sould I define fluid zone as dynamic mesh zone??!!

if you have a moving wall and a fluid right next to it, that fluid needs to be defined as a dynamic zone which is deforming

any other walls adjacent to the moving one need to be defined as deforming as well

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