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UDF for Syamlal obrein symmetric grag model (solid-solid)

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Old   October 23, 2018, 12:47
Default UDF for Syamlal obrein symmetric grag model (solid-solid)
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Muhammad Ali Uzair
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Hi,

Has anyone here written a udf for syamlal obrein symmetric model for solid solid interaction? Need help urgently.

I dont know how to include radial distribution function into that model.

Please do reply
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Old   October 23, 2018, 14:07
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I am simulating a three phase flow, and i want to write a udf for solid solid interaction.(SYAMLAL OBREIN SYMMETRIC DRAG MODEL)

I am facing two problems.

1) when i interpret udf, it shows me undeclared variable

line 19: l_col: undeclared variable

AND

`DEFINE_EXCHANGE_PROPERTY' used with too many (6) args





2) I dont know how to include radial distribution function in the udf

Can someone please point out the flaws and how to fix them

UDF is as follows

#include "udf.h"

#define diam2 0.0005
#define diam3 0.005
#define PI 3.141592654


DEFINE_EXCHANGE_PROPERTY(custom_drag,cell,mix_thre ad,g_col,s_col,l_col)
{
Thread *thread_g, *thread_l, *thread_s;
real x_vel_l, x_vel_s, y_vel_l, y_vel_s, abs_v, slip_x, slip_y,rho_l, rho_s;
real void_g,void_l,void_s,k_l_s;

/* find the threads for the gas phase */
/* and biomass (solid phase one) */
/* and sand (solid phase two) */

thread_g = THREAD_SUB_THREAD(mix_thread, g_col);/* gas phase */
thread_l = THREAD_SUB_THREAD(mix_thread, l_col);/* solid phase one */
thread_s = THREAD_SUB_THREAD(mix_thread, s_col);/* solid phase two*/

/* find phase velocities and properties*/

x_vel_l = C_U(cell, thread_l);
y_vel_l = C_V(cell, thread_l);

x_vel_s = C_U(cell, thread_s);
y_vel_s = C_V(cell, thread_s);

slip_x = x_vel_l - x_vel_s;
slip_y = y_vel_l - y_vel_s;

rho_l = C_R(cell, thread_l);
rho_s = C_R(cell, thread_l);

/*compute slip*/
abs_v = sqrt(fabs(slip_x*slip_x + slip_y*slip_y));


void_g = C_VOF(cell, thread_g);/* gas phase vol frac*/
void_s=1.-void_g-void_l;
void_l=1.-void_g-void_s;

k_l_s=(3*(1+0.9)*(PI*0.5)*void_s*rho_s*void_l*rho_ l*pow(diam2+diam3,2)*abs_v)/(2*PI*((rho_l*pow(diam2,3))+(rho_s*pow(diam3,3)))) ;

return k_l_s;
}
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Old   October 24, 2018, 23:56
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where did you get this macro?

from Ansys Fluent customization manual:
Code:
DEFINE_EXCHANGE_PROPERTY (name, c, mixture_thread,second_column_phase_index,first_column_phase_index)
I recommend to COMPILE UDF instead of interpretation

best regards
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Old   October 25, 2018, 04:59
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Muhammad Ali Uzair
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Quote:
Originally Posted by AlexanderZ View Post
where did you get this macro?

from Ansys Fluent customization manual:
Code:
DEFINE_EXCHANGE_PROPERTY (name, c, mixture_thread,second_column_phase_index,first_column_phase_index)
I recommend to COMPILE UDF instead of interpretation

best regards
Dear Thank you for the advice. Will the structure of the code remain same for the compiled udf?
P.S just a beginner :-)

I got it from this forum, shared by someone.
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drag, eulerian multiphase model, fluent, multiphase flow, udf

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