Introductory FLUENT Notes Fluent User Services cente ANSYS LUENT v6. 3 December 2006 wwfluentusers. com FLUENT The k-o Turbulence models The k-o family of turbulence models have gained popularity mainly because The model equations do not contain terms which are undefined at the wall, i.e. they can be integrated to the wall without using wall functions They are accurate and robust for a wide range of boundary layer flows with pressure gradient FLUENT offers two varieties of k-o models Standard k-o(SK W) model Most widely adopted in the aerospace and turbo-machinery communities Several sub-models/options of k-o: compressibility effects, transitional flows and shear-flow corrections Shear Stress Transport k-o(SSTK W) model(Menter, 1994) The Sstk-o model uses a blending function to gradually transition from the standard k-o model near the wall to a high Reynolds number version of the k-8 model in the outer portion of the boundary layer Contains a modified turbulent viscosity formulation to account for the transport effects of the principal tur bulent shear stress C 2006 ANSYS. nc All ANSYS, Inc. Proprietar© 2006 ANSYS, Inc. All rights reserved. 6-13 ANSYS, Inc. Proprietary Fluent User Services Center www.fluentusers.com Introductory FLUENT Notes FLUENT v6.3 December 2006 The k–ω Turbulence Models ◆ The k–ω family of turbulence models have gained popularity mainly because: ⚫ The model equations do not contain terms which are undefined at the wall, i.e. they can be integrated to the wall without using wall functions. ⚫ They are accurate and robust for a wide range of boundary layer flows with pressure gradient. ◆ FLUENT offers two varieties of k–ω models. ⚫ Standard k–ω (SKW) model ◼ Most widely adopted in the aerospace and turbo-machinery communities. ◼ Several sub-models/options of k–ω: compressibility effects, transitional flows and shear-flow corrections. ⚫ Shear Stress Transport k–ω (SSTKW) model (Menter, 1994) ◼ The SST k–ω model uses a blending function to gradually transition from the standard k–ω model near the wall to a high Reynolds number version of the k–ε model in the outer portion of the boundary layer. ◼ Contains a modified turbulent viscosity formulation to account for the transport effects of the principal turbulent shear stress