The Effects of Acoustical Disturbances on Boundary Layer Transition.
Annual rept. 15 Sep 75-15 Dec 77,
NEW YORK UNIV N Y DEPT OF APPLIED SCIENCE
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The analysis of transition from laminar to turbulent flow on a flat plate has been the subject of numerous investigations. In the present work, emphasis has been placed on establishing a computational technique which can be utilized to develop a basic understanding of the effects of the propagation of acoustic waves into a boundary layer, and the ultimate effect of such disturbances on transition. The nonlinear system of unsteady compressible partial differential equations have been solved by a MacCormack predictor-corrector scheme which allows the effect of imposed disturbances to be tracked in time. The question of the mismatch in propagation velocity between Tollmein Schlichting and acoustic waves has been studied. The program indicates that while disturbances are propagating with the speed of sound in the inviscid flow, the waves well within the boundary layer are propagating at a speed on the order of the freestream velocity and thus the boundary layer is being excited by the classical Tollmein Schlichting waves. The analysis thus indicates that the effect of acoustical disturbances on transition is similar to the effect of other perturbations as experiments have indicated. Author
- Numerical Mathematics
- Fluid Mechanics