CFD Online Discussion Forums - Falling box tutorial

Hello everyone. im working my thesis on the movement of particle on a submerged jet flow.

For the moment im having some troubles so i want to run the tutorial on a mm system. i modify the six dof udf on the mass and inertia values. and i run the case but when the box enter in contact with the water the case crash.

so the question its under wish parameters should i run the case?

#include "udf.h"

#define BMODULUS 2.2e9
#define rho_ref 1000.0

DEFINE_PROPERTY(water_density,c,t)
{
real rho;
real p, dp, p_operating;

p_operating = RP_Get_Real("operating-pressure");
p = C_P(c,t);
dp = p-p_operating;
rho = rho_ref/(1.0-dp/BMODULUS);

return rho;
}

DEFINE_PROPERTY(water_speed_of_sound,c,t)
{
real a;
real p, dp, p_operating;

p_operating = RP_Get_Real ("operating-pressure");
p = C_P(c,t);
dp = p-p_operating;
a = (1.-dp/BMODULUS)*sqrt(BMODULUS/rho_ref);

return a;
}

DEFINE_SDOF_PROPERTIES(falling_box, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 2.7e-6;
prop[SDOF_IZZ] = 4.5e-13;

printf ("\n2d_test_box: Updated 6DOF properties");
}

Under-Relaxation Factors

0.5 for Body Forces
0.8 for Turbulent Viscosity.

Solution Initialization

0.001 m2/s2 for Turbulent Kinetic Energy and 0.001 m2/s3 for Turbulent
Dissipation Rate.

1 for air Volume Fraction.