Hi All,

I am examining many different viscosity models through UDF's and have come across a problem. I have written a UDF for the Carreau model even though it is included in fluent, yet when I run 2 identical simulations, one with my UDf and one with fluent inbuilt Carreau model, they give different results, which makes me think I am using these Viscosity UDF's wrong for other models that aren't in Fluent. My UDF is below, is there a reason why this doesnt replicate the Carreau model in Fluent?

/* Carreau (p=2) Viscosity Model */

#include "udf.h"

float muinf=0.00345;

float mu0=0.056;

float lambda=3.313;

float p=2;

float n=0.3568;

DEFINE_PROPERTY(cell_viscosity,c,t)

{

real diff;

real shear;

real prod;

real power;

real visco;

diff=(mu0-muinf);

prod=((lambda)*(C_STRAIN_RATE_MAG(c,t)));

shear=(1+(pow(prod,p)));

power=((n-1)/(p));

visco=((muinf)+(diff)*(pow(shear,power)));

return visco;

}