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 Tamsu April 1, 2013 01:37

water sloshing in oscillating tank (problem using udf Define_ZONE_MOTION)

hello everyone,
I am simulating 2D sloshing of water due to oscillatory motion of a square tank. Here is a small description:
model=VOF: Implict, with zonal discretization.
gravity in 'y' dirctn.
Tank: 0.2m x 0.2m sqaure tank, closed walls.
Mesh: structured, finer at the water-air interface.
filled depth: 0.04m
UDF:
#include <udf.h>
DEFINE_ZONE_MOTION(fmotion,omega,axis,origin,veloc ity,time,dtime)
{
real velocity={0.6282*sin(62.82*time),0.0,0.0};
return;
}

UDF is hooked up with both of the cell zones.
Walls: moving walls, with relative velocity(adjacent to cell zone) =0 m/s
time-step size=0.0001 s
during calculation x and y velocity residuals are remaining almost constant until I reduce momentum URF to 0.001, then after the solution rapidly converges.
But water remains stationary as before. The free surface orientation does not change with time. even after 1 second of flow time.
Can anybody help me out?

 vasava April 2, 2013 06:49

1. Is there a space in 'DEFINE_ZONE_MOTION(fmotion,omega,axis,origin,veloc ity,time,dtime)' or just a typo?

2. It is possible that 1 sec is too short time to notice sloshing, try bit longer simulation.

 Tamsu April 2, 2013 08:00

Quote:
 Originally Posted by vasava (Post 417807) 1. Is there a space in 'DEFINE_ZONE_MOTION(fmotion,omega,axis,origin,veloc ity,time,dtime)' or just a typo? 2. It is possible that 1 sec is too short time to notice sloshing, try bit longer simulation.
Yeah, its a typo.
Time is surely not an issue. Instead of trying with a moving mesh, I varied a body force. Its giving good results even for small simulation time. Just that you wont see the mesh moving. but Its fairly sufficient for the analysis.

 vasava April 2, 2013 08:18

You said it first! I was just going to suggest that. So is everything fine now?

 Tamsu April 2, 2013 10:46

Yup!! everything is great! :)

 puneetnema November 9, 2013 10:24

sloshing

Quote:
 Originally Posted by Tamsu (Post 417481) hello everyone, I am simulating 2D sloshing of water due to oscillatory motion of a square tank. Here is a small description: model=VOF: Implict, with zonal discretization. gravity in 'y' dirctn. Tank: 0.2m x 0.2m sqaure tank, closed walls. Mesh: structured, finer at the water-air interface. filled depth: 0.04m UDF: #include DEFINE_ZONE_MOTION(fmotion,omega,axis,origin,veloc ity,time,dtime) { real velocity={0.6282*sin(62.82*time),0.0,0.0}; return; } UDF is hooked up with both of the cell zones. Walls: moving walls, with relative velocity(adjacent to cell zone) =0 m/s time-step size=0.0001 s during calculation x and y velocity residuals are remaining almost constant until I reduce momentum URF to 0.001, then after the solution rapidly converges. But water remains stationary as before. The free surface orientation does not change with time. even after 1 second of flow time. Can anybody help me out?
sir i m facing same problems...how did u rectify those..plz help me out

 samwize May 16, 2014 08:42

Sumit,

Can you please let me know how to go about solving this problem

Thanks,Samwize

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