On the Spatial Structure of Global Linear Instabilities And Their Experimental Identification

Abstract

The purpose of the present paper is to discuss the spatial structure of global instabilities, solutions of the partial derivative eigenvalue problem resulting from a nonparallel linear instability analysis of the incompressible Navier–Stokes and continuity equations, as developing upon four prototype essentially two-dimensional steady laminar flows. Theoretical knowledge of these eigendisturbances is instrumental to devising measurement techniques appropriate for their experimental recovery and ultimate control of laminar-turbulent transition mechanisms. Raising the awareness of the global linear flow eigenmodes contributes to redefining the boundaries between experimental observations which may be attributed to linear global as opposed to nonlinear mechanisms