FLUENT Fluent Software Trainin Ncct⊙tLD TRN-99-003 Two equation Model: Realizable k-c Distinctions from standard k-e model Alternative formulation for turbulent viscosity where is now variable U a+a I(Ao, As, and U* are functions of velocity gradients a Ensures positivity of normal stresses; u;>0 Ensures Schwarz's inequality;(uu, )'su: u? New transport equation for dissipation rate, E De a Pc.SE-pc, +.,g Diffusion Generation Destruction buoyancy C Fluent Inc. 2/20,D13 © Fluent Inc. 2/20/01 Fluent Software Training TRN-99-003 Two Equation Model: Realizable k-e u Distinctions from Standard k-e model: l Alternative formulation for turbulent viscosity where is now variable n (A0 , As , and U* are functions of velocity gradients) n Ensures positivity of normal stresses; n Ensures Schwarz’s inequality; l New transport equation for dissipation rate, e: e m r m 2 k t º C e m U k A A C o s * 1 + = u 0 2 i ³ 2 j 2 i 2 i j (u u ) £ u u b j t j c G k c k c S c Dt x x D e e e e ne e r e r e s m m e r 1 3 2 1 2 + + + - ú ú û ù ê ê ë é ¶ ¶ ÷ ÷ ø ö ç ç è æ + ¶ ¶ = Diffusion Generation Destruction Buoyancy