Water acoustic standing waves

The other studies, which included the effect of vibration on steam condensation, nucleate boiling heat transfer, and scale deposition, investigated the relation of frequency and amplitude of vibration of the heat transfer surface to increases in these heat transfer mechanisms. The study of the effect of acoustic vibrations in water on forced convection heat transfer investigated the influence of frequency and amplitude of the standing waves on increasing heat transfer rates and the flow Reynolds numbers at which increases could be obtained. 

An original method involves quadrupole oscillations of drops K The drop (a) in a host liquid (P) is acoustically levitated. This can be achieved by creating a standing acoustic wave the time-averaged second order effect of this wave gives rise to an acoustic radiation force. This drives the drop up or down in p, depending on the compressibilities of the two fluids, till gravity and acoustic forces balance. From then onwards the free droplet is, also acoustically, driven into quadrupole shape oscillations that are opposed by the capillary pressure. From the resonance frequency the interfacial tension can be computed. The authors describe the instrumentation and present some results for a number of oil-water interfaces. 

One of the reasons for the studies on the dynamical Casimir effect was Schwinger s hypothesis [153-157] that this effect could explain the sonolumi-nescence phenomenon, specifically, the emission of bright short pulses of the visible light from the gas bubbles in the water, when the bubbles pulsate because of the pressure oscillations in a strong standing acoustic wave. (Several reviews and numerous references related to this effect are available, [121,326-328].) There are several publications [329-331], whose authors considered the models giving tremendous numbers of photons that could be produced even in the visible range as a result of the fast motion of the boundaries. However, analysis of these models shows that they are based on such laws of motion of the boundaries that imply the superluminal velocities, so they are not realistic. 

The objective of this investigation was to determine the effects of vibration on heat 1 transfer and scaling mechanisms related to saline water conversion processes. During the initial phases of this study the effect of both vibration of the heat transfer surface and resonant acoustic vibrations in water on forced convection heat transfer was explored. Forced convection heat transfer was considerably more influenced by a vibrating heat transfer surface than by a standing acoustic wave in the flow medium. The major portion of this study was therefore concentrated on forced convection heat transfer from a vibrating heat transfer surface. 

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