Secondary Stability Analysis of Nonlinear Crossflow Vortices
Our work is concerned with the late stages of transition to turbulence in a three-dimensional (3D) boundary layer initiated by crossflow instability. Previously, we investigated the transition process in the 3D boundary layer on a swept flat plate by Direct Numerical Simulation (DNS) using the temporal model. In the present work, we investigate the secondary stability of the quasi-saturated state obtained from the DNS data at several stages before the onset of breakdown, employing a linear stability analysis. Our stability results show typical characteristics of the experimentally observed high-frequency instability. The instability frequencies and the structure of the eigenfunctions are in good agreement with experimental data.
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