{"id":360508,"date":"2024-04-04T14:36:39","date_gmt":"2024-04-04T14:36:39","guid":{"rendered":"\/forum\/forums\/topic\/swirl-velocity-gradient-in-2d-axisymmetric-domain\/"},"modified":"2024-04-04T14:36:39","modified_gmt":"2024-04-04T14:36:39","slug":"swirl-velocity-gradient-in-2d-axisymmetric-domain","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/swirl-velocity-gradient-in-2d-axisymmetric-domain\/","title":{"rendered":"Swirl velocity gradient in 2D axisymmetric domain"},"content":{"rendered":"

In a 2D, axisymmetric domain, I am modeling a turbulent swirl flow. I want the turbulent viscosity to be dependent on the velocity gradient in the y-direction (x-axis is the symmetry axis) of the swirl velocity. In the UDF, I use “C_W_G(c,t)[1]” to find the gradient of the swirl velocity. I can compile and load the UDFs, but when I start the initialization, the error : “999999 mpt_accept error accept failed no such file or directory ” occurs and fluent closes. The error does not occur when I use “C_U_G(c,t)[1]. <\/p>\n

#include “udf.h”<\/div>\n
 <\/div>\n
DEFINE_TURBULENT_VISCOSITY(user_mu_t,c,t)<\/div>\n
{<\/div>\n
  real mu_t;<\/div>\n
  real R;<\/div>\n
  real rho = C_R(c,t);<\/div>\n
  real L;<\/div>\n
  real y;<\/div>\n
  real dUdy = C_U_G(c,t)[1];<\/div>\n
  real dSwirldy = C_W_G(c,t)[1];<\/div>\n
  real x[ND_ND];<\/div>\n
  C_CENTROID(x,c,t);<\/div>\n
  y = x[1];<\/div>\n
  R = 0.05;<\/div>\n
 <\/div>\n
  L = R*(0.14 – 0.08*(y\/R)*(y\/R) – 0.06*(y\/R)*(y\/R)*(y\/R)*(y\/R) );<\/div>\n
 <\/div>\n
  mu_t = rho*L*L*pow( pow(dSwirldy,2.) ,0.5);<\/div>\n
 <\/div>\n
  return mu_t;<\/div>\n
}<\/div>\n","protected":false},"template":"","class_list":["post-360508","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t