Creo Flow Analysis > Preprocessing > Defining Physics > Turbulence > Physics > Turbulence Models
  
Turbulence Models
You can calculate the effective turbulent viscosity in a fluid system based on the eddy viscosity model. There are two models in the eddy viscosity model:
• Standard K-Epsilon Model
The Standard K-Epsilon model is a Turbulence model available in Creo Flow Analysis.
formulation for the Turbulent Kinetic Energy k is:
Standard K-Epsilon Model
formulation for the Turbulent Dissipation Rate ε is:
Standard K-Epsilon Model
where,
c1=1.44
constants C1
c2=1.92
constants C2
σk=1
turbulence kinetic energy Prandtl number
σz=1
turbulence dissipation rate Prandtl number
Turbulent Kinetic Energy
turbulent kinetic energy
v’
turbulent fluctuation velocity
turbulent energy dissipation rate
strain tensor
u’i(i=1,2,3)
components of the turbulent fluctuation velocity
Turbulent Viscosity
turbulent viscosity, with Cμ=0.09 and E=9.793
turbulence generation term
turbulence Reynolds stress
the Boussinesq approximation to the Reynolds Stress
References: Launder, B.E. & Spalding, D.B. (1974) “The numerical computation of turbulent flows,” Computer Methods, Applied Mechanics and Engineering, vol. 3, pp. 269-289
• Renormalization Group (RNG) K-Epsilon Model
The Renormalization Group (RNG) K-Epsilon model is a Turbulence model available in Creo Flow Analysis. This model is similar to the Standard K-Epilson model but with an expression involving two new constants that are used to modify the C2 RNG term in the equation below:
RNG K-Epsilon Model
Constant C2 in RNG model
Constant C2 in RNG model
where,
η0=4.38
RNG constant (a hard-coded constant in Flow Analysis )
β=1.92
RNG constant (a hard-coded constant in Flow Analysis )
P
local pressure
c1=1.44
constants C1
c2=1.92
constants C2
σk=1
turbulence kinetic energy Prandtl number
σz=1
turbulence dissipation rate Prandtl number
Turbulent Kinetic Energy
turbulent kinetic energy
v’
turbulent fluctuation velocity
turbulent energy dissipation rate
strain tensor
u’i(i=1,2,3)
components of the turbulent fluctuation velocity
Turbulent Viscosity
turbulent viscosity, with Cμ=0.09
turbulence generation term
turbulence Reynolds stress
Boussinesq approximation to the Reynolds stress
References: Yakhot, V., Orszag, S.A., Thangam, S., Gatski, T.B. & Speziale, C.G. (1992), "Development of turbulence models for shear flows by a double expansion technique", Phys. of Fluids A, Vol. 4, No. 7, pp1510-1520