Simulation of nonlinear instabilities in an attachment-line boundary layer
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چکیده
The linear and the nonlinear stability of disturbances that propagate along the attachment line of a three-dimensional boundary layer is considered. The spatially evolving disturbances in the boundary layer are computed by direct numerical simulation (DNS) of the unsteady, incompressible Navier-Stokes equations. Disturbances are introduced either by forcing at the in ow or by applying suction and blowing at the wall. Quasi-parallel linear stability theory and a nonparallel theory yield notably di erent stability characteristics for disturbances near the critical Reynolds number; the DNS results con rm the latter theory. Previously, a weakly nonlinear theory and computations revealed a high wave-number region of subcritical disturbance growth. More recent computations have failed to achieve this subcritical growth. The present computational results indicate the presence of subcritically growing disturbances; the results support the weakly nonlinear theory. Furthermore, an explanation is provided for the previous theoretical and computational discrepancy. In addition, the present results demonstrate that steady suction can be used to stabilize disturbances that otherwise grow subcritically along the attachment line. Running Title: Nonlinear Attachment-Line Instabilities Dr. Ronald D. Joslin Fluid Mechanics and Acoustics Division NASA Langley Research Center Mail Stop 170 Hampton, Virginia 23681-0001 (804)864-2234, Fax: (804)864-8801 E-mail: [email protected] Some results were originally presented as AIAA Paper No. 94-0826 at the AIAA 32nd Aerospace Sciences Meeting & Exhibit, January 10{13, 1994, Reno, NV.
منابع مشابه
Direct Simulation of Evolution and Control of Nonlinear Instabilities in Attachment{line Boundary Layers
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تاریخ انتشار 2007