[sofie1]

Hi ,
I am trying to simulate mhd flow in horizontal pipe with udf to calculate mhd body force , bf=(sigma/rho)*B*u

B is the magnetic induction,u is the velocity
so i write an udf but there is an error.
Does some body know this error


thanck you very much

[sofie1]

Originally Posted by sofie1

Hi ,
I am trying to simulate mhd flow in horizontal pipe with udf to calculate mhd body force , bf=(sigma/rho)*B*u

B is the magnetic induction,u is the velocity
so i write an udf but there is an error.
Does some body know this error


thanck you very much

************************************************** *******************


Magnetic Bodyforce calculation
************************************************** ********************/
#include "udf.h"


#define B_0 10. /* y component of magnetic field */
#define SIG 5.5E-6 /*electrical conductivity*/
#define rho 1239.1244

DEFINE_MAGNETIC-BODYFORCE(Cell_bforce, cell,thread)
{
real bforce,rho,veloc u;

veloc u=C-U(cell,thread);

bforce = -(SIG/rho)*B-0*B-0*veloc u;

return bforce;
}

[AlexanderZ]

fluent is using build in macros to execute with user's code
for your case you probably wanna go with DEFINE_SOURCE macro

#include "udf.h"

real B_0=10.0; /* y component of magnetic field*/
real SIG=5.5E-6; /*electrical conductivity*/
real rho=1239.1244;

DEFINE_SOURCE(Cell_bforce, cell, thread, dS, eqn)
{
	real source;
	real rho;
	real veloc_u;
	veloc_u = C_U(cell,thread);
	source = -(SIG/rho)*B_0*B_0*veloc_u;
	dS[eqn] = -(SIG/rho)*B_0*B_0;

	return source;
}

[sofie1]

Originally Posted by AlexanderZ

fluent is using build in macros to execute with user's code
for your case you probably wanna go with DEFINE_SOURCE macro

#include "udf.h"

real B_0=10.0; /* y component of magnetic field*/
real SIG=5.5E-6; /*electrical conductivity*/
real rho=1239.1244;

DEFINE_SOURCE(Cell_bforce, cell, thread, dS, eqn)
{
	real source;
	real rho;
	real veloc_u;
	veloc_u = C_U(cell,thread);
	source = -(SIG/rho)*B_0*B_0*veloc_u;
	dS[eqn] = -(SIG/rho)*B_0*B_0;

	return source;
}

Thank you very much AlexanderZ

The udf works well, but inserting it in another udf it doesn't work, please i need help;
/************************************************** *******************

Calculation of the properties of Fe3O4 nanoparticles
************************************************** ********************/
#include "udf.h"


#define FI 0.05
#define RHO_np 1398.194
#define SI_1 0.9830
#define SI_2 12.959
#define KTC_np 7
#define TI 5.E4
#define BETA_1 8.4407
#define BETA_2 -1.07304
#define CP_w 4181.8
#define KA 1.383E-23
#define SIi_1 2.8217E-2
#define SIi_2 3.917E-3
#define SIi_3 -3.0669E-2
#define SIi_4 -3.91123E-3
#define T_0 298.15
#define D_np 59.E-9
#define CP_np 640.0
#define B_0 10.0; /* y component of magnetic field */
#define SIG 5.5E-6; /*electrical conductivity*/
DEFINE_PROPERTY(cell_conductivity,cell,thread)
{
real ktc,ktc_w,temp,f,beta,rho_w;
temp = C_T(cell,thread);
f = ((SIi_1*FI+SIi_2*temp)/T_0)+(SIi_3*FI+SIi_4);
beta = BETA_1*(pow(100*FI,BETA_2));
rho_w = (-3.570*(pow(10,-3))*(pow(temp,2))+(1.88*temp+753.2));
ktc_w = (-8.354*0.000001*(pow(temp,2)))+((6.53*0.001*temp)-0.5981);
ktc = ((KTC_np+(2*ktc_w)-2*(ktc_w-KTC_np)*FI)/(KTC_np+(2*ktc_w)+(ktc_w-KTC_np)*FI))+(TI*beta*FI*rho_w*CP_w*(pow(((KA*temp )/(RHO_np*D_np)),0.5))*f);
return ktc;
}

DEFINE_PROPERTY(cell_density,cell,thread)
{
real temp,rho_w,rho;
temp = C_T(cell,thread);
rho_w = (-3.570*(pow(10,-3))*(pow(temp,2))+(1.88*temp+753.2));
rho = (FI*RHO_np)+((1-FI)*rho_w);
return rho;
}

DEFINE_PROPERTY(cell_viscosity,cell,thread)
{
real mu,mu_w,temp;
temp = C_T(cell,thread);
mu_w = (2.591*(pow(10,-5))*(pow(10,(238.3/(temp-143.2)))));
mu = (SI_1*exp(SI_2*FI)*mu_w);
return mu;
}

DEFINE_SOURCE(Cell_bforce, cell, thread, dS, eqn)
{
real source,rho_w,temp,veloc_u;


temp = C_T(cell,thread);
rho_w = (-3.570*(pow(10,-3))*(pow(temp,2))+(1.88*temp+753.2));

veloc_u = C_U(cell,thread);
source = -(SIG/rho_w)*B_0*B_0*veloc_u;
dS[eqn] = -(SIG/rho_w)*B_0*B_0;

return source;
}

[AlexanderZ]

was

#define B_0 10.0; /* y component of magnetic field */
#define SIG 5.5E-6; /*electrical conductivity*/

to be

#define B_0 10.0
#define SIG 5.5E-6

[sofie1]

Originally Posted by AlexanderZ

was

#define B_0 10.0; /* y component of magnetic field */
#define SIG 5.5E-6; /*electrical conductivity*/

to be

#define B_0 10.0
#define SIG 5.5E-6

Thank you very much but the error persists

[sofie1]

Attachment 92827Attachment 92827

Originally Posted by AlexanderZ

was

#define B_0 10.0; /* y component of magnetic field */
#define SIG 5.5E-6; /*electrical conductivity*/

to be

#define B_0 10.0
#define SIG 5.5E-6

Thanck you very much it run finally