Development of a one-equation Transition/Turbulence model

The development of a unified one-equation model for the prediction of trans itional and turbulent flows is described herein. An eddy-viscosity-transpor t equation for nonturbulent fluctuation growth based on that proposed by Wa rren and Hassan (Warren, E. S., and Hassan, H. A., "Transition Closure Mode l for Predicting Transition Onset ' "Journal of Aircraft, Vol. 35, No. 5,19 98, pp. 769-775) is combined with the Spalart-Allmaras one-equation model f or turbulent fluctuation growth. Blending of the two equations is accomplis hed through a multidimensional intermittency function based on the work of Dhawan and Narasimha (Dhawan, S., and Narashima, R., "Some Properties of Bo undary Layer Flow During Transition from Laminar to Turbulent Motion," Jour nal of Fluid Mechanics, Vol. 3, No. 4, 1958, pp. 418-436). The model predic ts both the onset and extent of transition. Low-speed test cases include tr ansitional flow over a flat plate, a single-element airfoil, a multielement airfoil in landing configuration, and a circular cylinder. Simulations of Mach 3.5 transitional flow over a 5-deg cone are also presented. Results ar e compared with experimental data, and the spatial accuracy of selected pre dictions is analyzed.