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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: formulation for the Turbulent Dissipation Rate ε is: 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 v’ turbulent fluctuation velocity turbulent energy dissipation rate strain tensor u’i(i=1,2,3) components of the turbulent fluctuation velocity 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:   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 v’ turbulent fluctuation velocity turbulent energy dissipation rate strain tensor u’i(i=1,2,3) components of the turbulent fluctuation velocity 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