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Acoustic Streaming: From Rayleigh to Today

This paper reviews the current state of knowledge of several classes of acoustic streaming. Acoustic streaming is classified based on the different mechanisms by which it is generated. For each category, the main achievements in terms of analysis, experimental work, and numerical simulation are described. An order of magnitude analysis, applicable to all types of acoustic streaming, is also given. This provides an additional means to classify acoustic streaming as either slow or fast, depending on the amplitude of the primary driving mechanism. The significant lack of understanding in the general area of fast streaming is noted, and the importance of the use of direct numerical simulations in the study of nonlinear streaming is emphasized. The paper concludes with a summary of the many challenges that are still faced by researchers in this field. The authors are pleased to contribute this paper in honor of Alan Powell's significant contributions to acoustics on the occasion of his eightieth birthday.