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Abstract
This study represents performance tests of the third-order turbulence closure for predictions of separating and recirculating flows in a backward-facing step. Computations of the momentum and temperature fields in the flow domain being considered entail the solution of the time-averaged transport equations containing the second-order turbulent fluctuating products. Formulations have been made for the triple products, which are responsible for the diffusive transport of the second-order products, by developing each corresponding transport equation. A low Reynolds number model associated with the viscous effect in near-wall regions is developed and incorporated in the present computation.
The computations are compared with several algebraic models and with the experimental data in literature. The prediction has been improved considerably, particularly in the separated shear layer.
Finally, several advantages have been observed in using the transport equations to evaluate the turbulence triple products; one of the most important features is that the transport model can always take the effects of convection and diffusion into account in strong convective shear flows such as reattaching separated layers, while conventional algebraic models cannot account for these effects in the evaluation of turbulence variables.