[Xiangfei]

Hi, I want to write a udf to define turbulent Prandtl. Below is part of my code. However, I can not Reproduce the results in the literature. I wonder I wonder if the calculating of yplus is wrong. please. The model of turbulent Prandtl please see the attachments. Thanks!
Snipaste_2018-08-03_11-31-42.jpgg.jpg
/* Specifying a Variable Temperature Prandtl Number */
#include "udf.h"
#include "math.h"
DEFINE_PRANDTL_T(Prt,c,t)
{
real pr_t; /* turbulent Prandtl */
real mu = C_MU_L(c,t); /* molecular dynamic viscosity */
real mu_t = C_MU_T(c,t); /* turbulent dynamic viscosity */
real thermalCon=C_K_L(c,t); /* molecular thermal conductivity */
real cp=C_CP(c,t); /* specific heat */
real pr_mol=mu*cp/thermalCon; /* molecular pr */
real density=C_R(c,t); /* molecular density */
real mu_ratio=mu_t/mu; /* mu_ratio */
real velocity_dudy=C_DUDY(c,t); /* velocity derivative */
real Tao_tur=mu*velocity_dudy; /* turbulence shear stress */
real velocity_F=sqrt(fabs(Tao_tur/density)); /* Friction Velocity */
real y;
real y_plus;
real x[2];
C_CENTROID(x,c,t);
y=x[1];
y_plus=density*velocity_F*(0.004-y)/mu; /* Friction Velocity */

if (y_plus<=5)
pr_t=1.0;
else if (y_plus<100 && y_plus>5)
pr_t=0.5+0.1*pr_mol/mu_ratio;
else
pr_t=0.85;

return pr_t;
}