Simulation of sloshing by time varying gravity
 

Hi I am trying to simulate sloshing in a tank. I tried solving the problem by adding a source term in the momentum equation using following code..

#include "udf.h" #define pie 3.141592654

DEFINE_SOURCE(cell_x_source, cell, thread, dS, eqn) { real source;

/* source term */

source=(-0.15)*pow((2*pie/1.70),2)*C_R(cell,thread)*sin((2*pie/1.70)*CURRENT_TIME);

dS[eqn] = 0.;

return source; }

I compared my results with published experimental and CFD results, and found that the change in freesurface with time is not matching.

Now I want to solve the problem by using a time varying gravity. Is follwing code sufficient ?

#include "udf.h" #DEFINE g 9.81 #DEFINE pie 3.14 #DEFINE timeperiod 1.70

DEFINE_ADJUST(my_adjust,d) { M_gravity[ND_ND]=g*sin((2*pie/timeperiod)*CURRENT_TIME); }

Thanks

Manoj

Re: Simulation of sloshing by time varying gravity
 

The codes are ..

#include "udf.h"

#define pie 3.141592654

DEFINE_SOURCE(cell_x_source, cell, thread, dS, eqn)

{

real source;

/* source term */

source=(-0.15)*pow((2*pie/1.70),2)*C_R(cell,thread)*sin((2*pie/1.70)*CURRENT_TIME);

dS[eqn] = 0.;

return source;

}

and

#include "udf.h"

#DEFINE g 9.81

#DEFINE pie 3.14

#DEFINE timeperiod 1.70

DEFINE_ADJUST(my_adjust,d)

{

M_gravity[ND_ND]=g*sin((2*pie/timeperiod)*CURRENT_TIME);

}

Dear friend, I utilized your posts very much.
I appreciate your activities.
Thanks a lot.
Saeed

gravity variation in Fluent?
 

Hi, for the second method, I've tried to implement your code in Fluent 6.3 but it can not recognize the item "M-gravity".

Does anyone know the definition of gravity in Fluent code,? I can't find it in the udf manual.