Streak stability in the suction boundary layer

A study of the stability characteristics of streamwise streaky structures in parallel boundary layer flow above a porous surface is conducted. The analytical solution for the perturbed velocities is sought by applying Fourier transformation in the spanwise direction and Laplace transformation in time. Assuming a localized initial perturbation in the y-direction and applying inverse Laplace transform the solution in wave number space is obtained.

The obtained flow shows non-algebraic initial growth. The streamwise velocity component reaches largest amplitudes for small spanwise wavenumbers and the initial perturbation placed in the boundary layer. For both vertical and streamwise velocities the amplitude peak diffuses towards the boundary in time, and a change of the amplitude sign occurs for some values of the parameters.

Author: Davidsson, Niklas

Source: LuleƄ University of Technology

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