A COMBINED EXPERIMENTAL AND COMPUTATIONAL STUDY OF PRESSURE-DRIVEN 3-DIMENSIONAL SEPARATION IN A TURBULENT BOUNDARY-LAYER

Experimental data and computational results are compared for a pressur e-driven three-dimensional separation in a two-dimensional turbulent b oundary layer. The comparisons include surface-flow visualizations, wa ll static pressures, and skin-friction coefficients. With the use of a n open-circuit low-speed wind tunnel, the separation pattern was gener ated by a streamwise adverse pressure gradient combined with localized overhead suction that represented 6% of the test section entrance flo w. This separation pattern was characterized by its topological critic al points: a saddle point of separation, a nodal point of attachment, two additional saddle points, and two foci. Calculations of the experi ment were made by using the INS3D computer code with the Spalart-Allma ras one-equation turbulence model. The topology of the computed near-w all particle traces was similar to the experimental separation pattern having the same geometric aspect ratio and the same number and types of critical points seen in the experiment. Comparisons between experim ental data and computed results for static-pressure coefficient and sk in-friction coefficient also showed good agreement. Results from the u se of another turbulence model, Baldwin-Barth, had a much larger separ ated region. This experiment provides new data that isolate a three-di mensional separation pattern driven by pressure gradient and the amoun t of turbulent mixing. (C) Elsevier Science Inc., 1996