Predicting S-Duct Flow Using a Composite Algebraic Stress Model

Abstract

An incompressible composite algebraic stress model is presented that accounts for dissipation rate anisotropies and that is validated against S-duct flow. The component algebraic stress and algebraic, anisotropic dissipation rate models have been developed previously, and tested against homogeneous flow. The composite model is developed for integration to the wall and is calibrated against high-Reynolds number plane channel flow data to ensure the correct log-law behavior. The model is validated and analyzed against turbulent flow in an S duct. Both predicted mean flow quantities and turbulence statistics are compared with experimental data, as well as with an isotropic eddy viscosity model and an algebraic stress model with an isotropic dissipation rate. The experimentally observed lag between the shear stress vector direction and the mean velocity-gradient vector direction is qualitatively predicted. The effects of anisotropic dissipation rate on the production of the dissipation term in the dissipation rate equation and on the scalar functions that multiply the linear and nonlinear terms in the tensor expansion are examined relative to the algebraic stress formulation with an isotropic eddy viscosity.