A Note on the Oscillation of Cavities Coupled to Aerodynamic Flows,
INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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The extensive recent literature on the oscillation of cavities interacting with aerodynamic flows has resulted in a bewildering array of models for frequency prediction, each of which may have theoretical or experimental bases for various of the physical processes being modeled to describe the overall system. Such models have generally been built on various representations of two physical phenomena and their interaction the instability of vortex sheets between fluid layers of differing velocities and the acoustic resonance of cavities. Surprisingly, most of the models fit at least some set of experimental data amazingly well, especially in view of the complex interacting physical phenomena with which they deal. Almost all of the models ccan be rationalized within the phenomenological framework of a formula due to Rossiter. However, in this contex it seems that what this subject has evolved into is a mathematical theory of integral wavelengths. The overlapping and sometimes hidden assumptions in models for cavity oscillation often tend to obscure rather than clarify the mechanics of aerodynamically driven cavity oscillations. In this note, some relations between the physical phenomena contemplated in various models are discussed.