Introductory FLUENT Notes Fluent User Services cente ANSYS LUENT v6. 3 December 2006 wwfluentusers. com FLUENT The k-e Turbulence models Realizable k-8(RKE)model o The term realizable means that the model satisfies certain mathematical constraints on the reynolds stresses, consistent with the physics of turbulent fle a Positivity of normal stresses: uu >0 SchwarZ' inequality for Reynolds shear stresses:(uu; ) suu Neither the standard k-e model nor the rng k-e model are realizable Benefits More accurately predicts the spreading rate of both planar and round jets Also likely to provide superior performance for flows involving rotation boundary layers under strong adverse pressure gradients, separation, and recirculation C 2006 ANSYS. nc All ANSYS, Inc. Proprietar© 2006 ANSYS, Inc. All rights reserved. 6-12 ANSYS, Inc. Proprietary Fluent User Services Center www.fluentusers.com Introductory FLUENT Notes FLUENT v6.3 December 2006 The k–ε Turbulence Models ◆ Realizable k–ε (RKE) model ⚫ The term realizable means that the model satisfies certain mathematical constraints on the Reynolds stresses, consistent with the physics of turbulent flows. ◼ Positivity of normal stresses: ◼ Schwarz’ inequality for Reynolds shear stresses: ⚫ Neither the standard k–ε model nor the RNG k–ε model are realizable. ⚫ Benefits: ◼ More accurately predicts the spreading rate of both planar and round jets. ◼ Also likely to provide superior performance for flows involving rotation, boundary layers under strong adverse pressure gradients, separation, and recirculation. ( ) 2 2 2 ui uj  ui uj   ui  u  j  0