by Mohammed S. Kamel Reliable prediction of optical wavefront distortions induced by compressible turbulent flow surrounding an aperture is crucial to the development of airborne laser systems. Large-eddy simulation (LES) with a wall model provides a promising highfidelity simulation method for high-Reynolds-number aero-optical flows by avoiding the severe near-wall resolution requirement. In t...

The paper I s a revlew of sound generatlon In turbulent shear flows. It emphasizes slmultaneous 0 calculatlon of the turbulent flow along wlth the ' h cr) resulting sound generatlon rather than the alternaI tlve acoustlc analogy approach. The first part of w the paper I s concerned wlth solld surface lnteractlon. The second part concentrates on the sound generated by turbulence Interacting wlth...

Scientific problems related to modern aeronautical engineering and dealing with basic properties of shear flows and the associated fluid mechanics phenomena are emphasized. In this context some recent experimental results on subsonic aerodynamics are considered.

Two examples of explosive events observed with SUMER in transition region spectral lines are reported here; one detected in C iv 1548 Å, in a region within the northern polar coronal hole, and the other in O vi 1032 Å, in an active region. The event measured in C iv lasted ∼ 3 min and extended approximately a region of 8 arc sec along the slit (N-S) and 8 arc sec in the E-W direction. Velocitie...

An adaptive control system using extremum-seeking optimization is developed to suppress subsonic cavity flow oscillations. The overall control system is developed by following two steps. First, a simple linear control law which uses measurements of wall pressure fluctuations at two different locations in the cavity is developed, and the effect on the magnitude of the limit cycle produced by tun...

A compensated compactness framework is established for sonic-subsonic approximate solutions to the two-dimensional Euler equations for steady irrotational flows that may contain stagnation points. Only crude estimates are required for establishing compactness. It follows that the set of subsonic irrotational solutions to the Euler equations is compact; thus flows with sonic points over an obsta...