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Numerical Simulations of the Control of Wave Packet Disturbances in the Boundary Layer on a Flat Plate

出版	Defense Technical Information Center, 1992
URL	http://books.google.com.hk/books?id=UQr0jwEACAAJ&hl=&source=gbs_api

註釋The control of laminar turbulent transition in incompressible flat plate boundary layers is investigated using direct numerical simulations. The investigations focus in particular on the control of wave packet disturbances that are characteristic for natural transition. A fully implicit finite difference/spectral method was developed to solve the governing equations. Wave packet disturbances are created by simulating the effect of thermally activated heater elements on the plate surface. Through controlled spanwise variation of the temperature of the heater elements, both two-and three-dimensional wave packet disturbances could be investigated. A transfer function technique was developed for the control strategy, where the transfer function is obtained directly from the numerical simulations. With this technique low amplitude, two- dimensional wave packet disturbances could be almost completely cancelled. Using a modified transfer function technique the control of three-dimensional wave packets was also very successful. It was found that the attenuation of only the two-dimensional components of a three-dimensional wave packet considerably delays the onset of the nonlinear interactions of the oblique modes ... Direct numerical simulations, Transition control, Wave packets, Laminar -Turbulent transition, Computational fluid dynamics.