Calculation of two-dimensional turbulent boundary layers using the Baldwin-Lomax model

Abstract

THE algebraic turbulent eddy-viscosity model of Baldwin and Lomax is critically evaluated for a class of twodimensional, nonseparated, turbulent boundary-layer flows exhibiting adverse and favorable pressure gradients, and boundary-layer bleed. The flows are computed using the twodimensional, mass-averaged, boundary-layer equations. Overall, the results obtained using the Baldwin-Lomax model compare favorably with the experimental data. Two quantities in the outer eddy-viscosity formulation are examined by comparison with the eddy-viscosity model of Cebeci and Smith. Contents The present capabilities for numerical simulation of highspeed turbulent flows are based on a variety of turbulence models. Algebraic eddy-viscosity models are still among the most popular. Certain algebraic models require the determination of the boundary-layer edge velocity and thickness, which can result in large variations in the computed outer eddy viscosity due to the uncertainty in determining the boundarylayer edge.1 Baldwin and Lomax1 have developed a two-layer, algebraic eddy-viscosity model in an attempt to eliminate this difficulty. This model has been patterned after the model of Cebeci and Smith2; however, it does not require the determination of the boundary-layer edge. The Baldwin-Lomax turbulence model was evaluated by its originators for several cases, including a shock-wave, turbulent boundary-layer interaction on a flat plate, a supersonic turbulent compression corner, and a transonic airfoil.1 Visbal and Knight3 noted that the constants Ccp and CKleb in the Baldwin-Lomax outer formulation were dependent on flow Mach number. They also identified difficulties with the determination of the length scale in the outer eddy viscosity. Similar difficulties have been encountered by other computers.4 Despite the difficulties identified with the BaldwinLomax model, and its increasing popularity and extensive application to two- and three-dimensional flows with strong viscous-inviscid interaction, a critical evaluation of this model for nonseparated, two-dimensional, turbulent boundary-layer flows has not been performed. The present investigation seeks to contribute to the evaluation of the model by critically examining its performance for a class of turbulent boundarylayer flows. Baldwin and Lomax determined the constants Ccp and CKleb appearing in the outer formulation1 by comparison with the Cebeci-Smith model for transonic, constant-pressure,