Scaling of boundary-layer disturbances exposed to free-stream turbulence

We present theoretical results related to the experimental findings of Matsubara & Alfredsson (J. Fluid Mech., vol. 430, 2001, pp. 149-168) on the scaling of the energy spectra of the Klebanoff modes, i.e. streamwise-elongated vortical disturbances generated by free-stream turbulence in a flat-plate transitional boundary layer. The scaling is explained by a model that describes the streamwise evolution of the streamwise and spanwise energy spectra. The theoretical framework is based on the quasi-steady asymptotic solution of the boundary-region equations, on an axial-symmetric model of the free-stream spectrum, and on the spectral response of the boundary layer to the external perturbations.

Automated summary

This study presents theoretical results related to the experimental findings of the energy spectra of streamwise-elongated vortical disturbances generated by free-stream turbulence in a flat-plate transitional boundary layer. The scaling of the energy spectra is explained using a model that describes the streamwise evolution of the streamwise and spanwise energy spectra.