波涡相互作用研究的某些进展(Ⅱ)

WAVE-VORTEX INT ERACT IONS (II)

5 波涡共振 从第3节的感受性问题再前进一步,自然要问在什么条件下入射波激发起涡中之波的最大响应.这就导致了入射波与层状或轴状涡中受激波之间共振的概念,简称波涡共振.一般说来,在流体内部若有两个或多个波相会,它们将互相穿透而沿原来的方向离去.但若它们的波矢量和频率满足一定的关系(参见Craik 1985),就会在相会点产生新的波.2阶扰动的振幅可达到1阶扰动振幅的量级,而且流场中会出现一些重要的独特性质.这就是流体内部波共振,波涡共振是其一类情形.

Wave7vortex interaction is one of crucial fields of modern nonlinear unsteady fluid dynamics. This paper presents a systematic review on the progress of studies on the interactions between weak, longitudinal and transverse waves (e. g., acoustic and vortical waves) and laminal and axial vortices. The review covers the vortex sound theory, the two-dimensional theory on receptivity and unsteady Kutta condition for the vortex layer separation from sharp edge and smooth surface as well as the free vortex layer, the nonlinear Eulerian and generalized Lagrangian streaming theory for wave-induced vortex flows, and the wave-vortex resonance. The paper also describes some important recent works on vortex flow control by unsteay excitation, including unsteady controls of separation and reattachment, unsteaey enhancement of vortex lift, and the unsteady control of vortex breakdown. These developments have revealed their great potential in various applications, and are of great theoretical interest. However, more extensive experiments on the mechanism of interaction, more effective computational methods and better theoretical models are desired for practical engineering applications.