[kishoreranganath]

Hi all,

I'm trying to simulate a liquid piston model. Water is being used to compress air in a chamber. There is no intermixing between the two fluids, and hence i did not use VOF (hope that is correct!). Now, I want to see how a solid body floating on water would affect the process. I have run few experiments and have the results with me. But, I'm not able to model the same. Please find attached the image of the setup I created on WB.

In the image, zone 1 is where the water enters and pushes the solid surface to compress air which is present in that chamber. I tried using a UDF, but that did not work. When I ask for motion preview it says that the solid in the middle has no surface.

The UDF that I used:

#include <udf.h>
DEFINE_CG_MOTION(vel_liquid_piston, dt, cg_vel, cg_omega, time, dtime)
{

cg_vel[0] = 0.005;
cg_vel[1] = 0.0;
cg_vel[2] = 0.0;
NV_S (cg_omega, =, 0.0);

}

Kindly help me with this simulation!

Thanks in advance!