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Old   September 6, 2007, 22:55
Default Sloshing
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I am doing a sloshing problem. I define my boundary conditions as functions of time and don't have fluid draining from my tank(boundary condition is wall).

-The solver must be unsteady (1st order implicit)

-the multiphase model is obviously VOF. Turn on the implicit body force option

-the viscous model is laminar

-set the phases. The primary phase should be the lighter

-on the operating conditions panel, enable gravity and specify the operating density as the one of the lighter phase.

-on the boundary conditions panel, turn on the source terms and use my momentum source

-keep my URFs quite big (0.6 and 0.8 for pressure and momentum respectively, 1 for the other parameters)

-discretization schemes: BODY FORCE WEIGHTED for pressure, PISO for pressure velocity coupling (skewness correction=1, neighbour correction=1, turn on the skewness neighbor coupling), FIRST ORDER UPWIND for momentum.

-once I initialize the flow field to create an adaption register for patching the initial fluid location (adapt>region, then patch the liquid volume fraction solve>initialise>patch, select the volume fraction of the liquid as 1)

-keep my time step quite small(0.001).

This is my UDF

#include "udf.h"

double AlnrX;

DEFINE_ADJUST(Accl, domain) { double t;

t = RP_Get_Real("flow-time");

AlnrX = -0.0363*sin(1.1*t);

printf("time = %f\n",t); printf("accel = %f\n",AlnrX);


DEFINE_SOURCE(xmom_source, cell, thread, dS, eqn) { double pos[ND_ND]; double rho; double source;


rho = C_R(cell,thread);

dS[eqn] = 0.0; source = AlnrX *rho;

return source; }

But my calculation is wrong comparing with experiment. Please tall me what is wrong on my setting.

Thank you very much!

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Old   September 7, 2007, 06:11
Default Re: Sloshing
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How is it wrong?

Grid and timestep independance?

Higher order spatial and temporal discretisation?

Start with a simple dam breaking validation to check your numerics.
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