Learning Forum

[Max]

Dear Experts,

I am trying to make 2-dimension UDF code for turbulent viscosity of the realizable k-e model. I want to ask about the expression term U* (See the attached figure).

I wonder what the eijk in the equation to estimate the mean rate-of -rotation is.

Since the mean rate-of rotation and the angular speed have unit 1/s. The eijk here should be the constant not the turbulent dissipation rate?

Thank you very much.

Here is the UDF code:

DEFINE_PROPERTY(tur_vis,c,t)
{
  real mu_tur;
  real S11, S12, S22, W12, W12r;
  real SMU, WAS, PHI, USTAR;
  real AS;
  real CMU, y, a1, a2, a3, a4, a5, a6, ;/***
  real betas=0.09;
  real A0=4.04;
  real rho=C_R(c,t);
  real k=C_K(c,t);
  real w=C_D(c,t);
  real CMUL=C_MU_L(c,t)
  real y=C_WALL_DIST(c,t);
  real S=C_STRAIN_RATE_MAG(c,t);

/***
  S11=0.5*(C_DUDX(c,t)+C_DUDX(c,t));
  S12=0.5*(C_DUDY(c,t)+C_DVDX(c,t));
  S22=0.5*(C_DVDY(c,t)+C_DVDY(c,t));

  W12=0.5*(C_DVDX(c,t)-C_DUDY(c,t));

/*** Cal vorticity with rotation ***/

  W12r=W12-wr*ce;

/*** Cal U*  ***/

  USTAR=sqrt(S11*S11+2*S12*S12+S22*S22+W12r*W12r);

/*** Cal Phi ***/

  SMU=sqrt(S11*S11+2*S12*S12+S22*S22);
  WAS=(pow(S11,3)+pow(S22,3)+3*pow(S12,2)*(S11+S22))/pow(SMU,3);
  PHI=1/3*acos(sqrt(6)*WAS);

/*** Cal As ***/

  AS = sqrt(6)*cos(PHI);

/*** Cal CMU ***/

  CMU=1/(A0+AS*USTAR/betas/w);

....

 

[abhishek.roy]

here eijk is a constant