UDF for Herschel-Bulkely model

emad · June 2, 2009, 12:49

Dear All
I would to used Herschel-Bulkely model but my model don't have Yielding Viscosity. Can be any body help me to use model in Fluent for Herschel-Bulkely model only don't have the Yielding Viscosity term. Please, If any body have UDF for Herschel-Bulkely model send me.
Many Thanks for help me
Emad

laurentb · June 17, 2009, 09:33

#include "udf.h"
#include "mem.h"
DEFINE_PROPERTY(cell_viscosity, cell, thread)
{
real mu_lam;
real K=134.0;
real A=0.17;
real gamma;
real strain=C_STRAIN_RATE_MAG(cell, thread);
if(strain==0)
{
gamma=11.126;
}
else
{
gamma=strain;
}
mu_lam=K*pow(gamma,(A-1));
return mu_lam;
}

emad · June 20, 2009, 02:54

Dear Lauren
Meny Thanks for reply. But I have some quations what mean terms K and A, I thanks the Herschel-Bulkley model have fluid yield stress where this term in your eqation. I would like to send me all terms with definetion.

Emad A.
My e-mail Emad_ab74@yahoo.com

laurentb · June 22, 2009, 02:02

A power law index, K consistency
add the yield stress in the definition of mu_lam
mu_lam=K*pow(gamma,(A-1)) + yield_stress/gamma;

emad · July 6, 2009, 15:26

Dear Lauren
Meny Thanks for reply. I don't understand this term
if(strain==0)
{
gamma=11.126;

the number 11.126 from where equation.

Many Thanks again fro help me

laurentb · July 20, 2009, 08:16

i don't know exactly but it will be better to write something like
if strain < strain_min then mu_lam=mu_min
if strain > strain_max then mu_lam=mu_max

June 2, 2009, 12:49	UDF for Herschel-Bulkely model	#1
emad New Member emad khazal Join Date: Mar 2009 Posts: 23 Rep Power: 17	Dear All I would to used Herschel-Bulkely model but my model don't have Yielding Viscosity. Can be any body help me to use model in Fluent for Herschel-Bulkely model only don't have the Yielding Viscosity term. Please, If any body have UDF for Herschel-Bulkely model send me. Many Thanks for help me Emad

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June 17, 2009, 09:33		#2
laurentb Member Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 16	#include "udf.h" #include "mem.h" DEFINE_PROPERTY(cell_viscosity, cell, thread) { real mu_lam; real K=134.0; real A=0.17; real gamma; real strain=C_STRAIN_RATE_MAG(cell, thread); if(strain==0) { gamma=11.126; } else { gamma=strain; } mu_lam=K*pow(gamma,(A-1)); return mu_lam; }

June 20, 2009, 02:54		#3
emad New Member emad khazal Join Date: Mar 2009 Posts: 23 Rep Power: 17	Dear Lauren Meny Thanks for reply. But I have some quations what mean terms K and A, I thanks the Herschel-Bulkley model have fluid yield stress where this term in your eqation. I would like to send me all terms with definetion. Emad A. My e-mail Emad_ab74@yahoo.com

June 22, 2009, 02:02		#4
laurentb Member Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 16	A power law index, K consistency add the yield stress in the definition of mu_lam mu_lam=K*pow(gamma,(A-1)) + yield_stress/gamma;

July 6, 2009, 15:26		#5
emad New Member emad khazal Join Date: Mar 2009 Posts: 23 Rep Power: 17	Dear Lauren Meny Thanks for reply. I don't understand this term if(strain==0) { gamma=11.126; the number 11.126 from where equation. Many Thanks again fro help me

July 20, 2009, 08:16		#6
laurentb Member Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 16	i don't know exactly but it will be better to write something like if strain < strain_min then mu_lam=mu_min if strain > strain_max then mu_lam=mu_max