The scattering of sound by the nonlinear interaction of two sound beams in the presence of turbulence is used to experimentally measure the turbulent velocities generated by a submerged water jet. When two sound beams of primary frequencies f01 and f02 intersect in a region of turbulent flow, the nonlinear scattering generates sum and difference frequency components (f0+ = f01 f02 and f0- = f01 - f02) which radiate outside the interaction region. In the absence of turbulence, the crossed beams do not produce radiated sum and difference frequencies. In this experiment, two transducers emit continuous wave focused sound beams of frequencies f01 = 2.0 MHz and f02 = 2.1 MHz, respectively. A receiving transducer, located outside the interaction region, detects the scattered sum frequency (f0 = 4.1 MHz.) Scattering results measured at 80 degree angles for each of 11 scan positions across the jet are used to map out the velocity correlation coefficients of the turbulence. Results are then compared with earlier published experiments that use conventional hotwire probes to measure a similar turbulent jet flow in air. nonlinear acoustics; sound- scattering; sound-waves; ultrasonic-waves.

This book contains a thorough and unique record of recent advances in the important scientific fields fluid–structure interaction, acoustics and control of priority interest in the academic community and also in an industrial context regarding new engineering designs. It updates advances in these fields by presenting state-of-the-art developments and achievements since the previous Book published by Springer in 2018 after the 4th FSSIC Symposium. This book is unique within the related literature investigating advances in these fields because it addresses them in a complementary way and thereby enhances cross-fertilization between them, whereas other books treat these fields separately.

These proceedings primarily focus on advances in the theory, experiments, and numerical simulations of turbulence in the contexts of flow-induced vibration and noise, as well as their control. Fluid-related structural vibration and noise problems are often encountered in many engineering fields, increasingly making them a cause for concern. The FSSIC conference, held on 5-9 July 2015 in Perth, featured prominent keynote speakers such as John Kim, Nigel Peake, Song Fu and Colin Hansen, as well as talks on a broad range of topics: turbulence, fluid-structure interaction, fluid-related noise and the control/management aspects of these research areas, many of which are clearly interdisciplinary in nature. It provided a forum for academics, scientists and engineers working in all branches of Fluid-Structure-Sound Interactions and Control (FSSIC) to exchange and share the latest developments, ideas and advances, bringing them together researchers from East and West to push forward the frontiers of FSSIC, ensuring that the proceedings will be of interest to a broad engineering community.

Since the human organism is itself an open system, we are naturally curious about the behavior of other open systems with fluxes of matter, energy or information. Of the possible open systems, it is those endowed with many degrees of freedom and strongly deviating from equilibrium that are most challenging. A simple but very significant example of such a system is given by developed turbulence in a continuous medium, where we can discern astonishing features of universality. This two-volume monograph deals with the theory of turbulence viewed as a general physical phenomenon. In addition to vortex hydrodynamic turbulence, it considers various cases of wave turbulence in plasmas, magnets, atmosphere, ocean and space. A sound basis for discussion is provided by the concept of cascade turbulence with relay energy transfer over different scales and modes. We shall show how the initial cascade hypothesis turns into an elegant theory yielding the Kolmogorov spectra of turbulence as exact solutions. We shall describe the further development of the theory discussing stability prob lems and modes of Kolmogorov spectra formation, as well as their matching with sources and sinks. This volume is dedicated to developed wave turbulence in different media.