I am trying to do a simple sloshing problem but I'm a bit confused how to perform it. I would like to sway (oscillatory x-motion) a 2D box as so: x = Amplitude * sin(omega * time). The box center is at (0,0) for simplicity. I know the amplitude and omega. I just don't know how to perform this task in Fluent. Any suggestions would rock! Thanks all!

-Brian

Hi Brian

You can do this by adding time varying momentum source to the momentum equation using following udf ...

#include "udf.h"

#define pie 3.141592654

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

/* source term */

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

/* derivative of source term w.r.t. x-velocity. */

dS[eqn] = 0.;

return source; }

You can also use a time varying gravity or a combination of these to simulate real problems.

Good luck

Manoj

Source equation should be

source =(-Amplitude*density)*pow((2*pie/time),2)*C_R(cell,thread)*sin((2*pie/time)*CURRENT_TIME); (N/m3)

I think the first version of your source term was correct. Now you have density squared (from Amplitude*density and C_R(c,t)) which is wrong. Although you dont have to define pie, you can use M_PI instead.

Regards

RoM

You are right.

Thanks Rom

Where I do input amplitude and omega ("time" in your example)? Do I define them in the UDF?

NEVERMIND! STUPID QUESTION!!!! HAHAHAHA!!