Introductory FLUENT Notes Fluent User Services cente ANSYS LUENT v6. 3 December 2006 wwfluentusers. com FLUENT Calculating turbulent Viscosity Based on dimensional analysis, Hr can be determined from a turbulence time scale(or velocity scale)and a length scale Turbulent kinetic energy [L/T2] k=u/2 Turbulence dissipation rate [L2/T3] &=v Ou /Ox, (Ou /Ox,+Ou /ax, Specific dissipation rate [1/T c/k Each turbulence model calculates uT differentl Spalart-Allmaras Solves a transport equation for a modified turbulent viscosity Standard k-8. rnG k-e Realizable k-e Solves transport equations for k and e k ● Standard k0.SSTk0 a Solves transport equations for k and o pk T C 2006 ANSYS. nc All ANSYS, Inc. Proprietar© 2006 ANSYS, Inc. All rights reserved. 6-9 ANSYS, Inc. Proprietary Fluent User Services Center www.fluentusers.com Introductory FLUENT Notes FLUENT v6.3 December 2006 ◆ Based on dimensional analysis, μT can be determined from a turbulence time scale (or velocity scale) and a length scale. ⚫ Turbulent kinetic energy [L2 /T2 ] ⚫ Turbulence dissipation rate [L2 /T3 ] ⚫ Specific dissipation rate [1/T] ◆ Each turbulence model calculates μT differently. ⚫ Spalart-Allmaras: ◼ Solves a transport equation for a modified turbulent viscosity. ⚫ Standard k–ε, RNG k–ε, Realizable k–ε ◼ Solves transport equations for k and ε. ⚫ Standard k–ω, SST k–ω ◼ Solves transport equations for k and ω. Calculating Turbulent Viscosity 2 i i k = u  u  ( ) i j i j j i  =  u  x u  x + u  x =  k  = () ~ f T            = 2 k f T          = k f T