Session Cc - General Instabilities.
ORAL session, Sunday, November 23
303, Moscone Center
Here we consider the stability of flow along a streamwise corner formed by the intersection of two large flat plates held perpendiclar to each other. Solutions for the steady laminar mean flow have been obtained for zero and non-zero streamwise pressure gradient. The stability of the mean flow is examined using linear stability analysis and a novel eigensolver has been developed to solve the resulting eigenvalue problem. Stability results indicate that the entire spectrum of modes of a Blasius boundary layer is active in the corner layer. The effect of the corner on the two dimensional Blasius viscous instability is to superpose a spanwise standing wave pattern and decrease the growth rate. The growth rate for oblique disturbances is decreased for outgoing modes and enhanced for incoming modes. The instability at zero pressure gradient is dominated by viscous modes; however, an inviscid corner mode is also observed. At zero pressure gradient this inviscid mode remains stable at very high Reynolds number, but the critical Reynolds number rapidly decreases with even a small adverse streamwise pressure gradient and the inviscid mode becomes the dominant one.