Introduction to nonlinear acoustics

Björnö, L.

doi:10.1016/j.phpro.2010.01.003

Cited by 32 publications

(16 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nonlinear acoustics is based on a nonlinear theory of elasticity [5]. Once the original sinusoidal finite-amplitude wave propagates from an ultrasonic source into a fluid medium, the wave will be exposed to two effects influencing its time course: (1) the dissipation arising from viscosity, heat conductivity, and relaxation processes and (2) the nonlinearity leading to the formation of higher harmonics to the fundamental frequency of the wave [6]. Understanding the basic mechanisms of the nonlinear effects of intense acoustic waves is critical to studying the distribution of high-intensity acoustic waves in a system [7].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Kewalramani

Zou²,

Marsh

et al. 2020

Acoustics

View full text Add to dashboard Cite

In this paper, nonlinearity associated with intense ultrasound is studied by using the one-dimensional motion of nonlinear shock wave in an ideal fluid. In nonlinear acoustics, the wave speed of different segments of a waveform is different, which causes distortion in the waveform and can result in the formation of a shock (discontinuity). Acoustic pressure of high-intensity waves causes particles in the ideal fluid to vibrate forward and backward, and this disturbance is of relatively large magnitude due to high-intensities, which leads to nonlinearity in the waveform. In this research, this vibration of fluid due to the intense ultrasonic wave is modeled as a fluid pushed by one complete cycle of piston. In a piston cycle, as it moves forward, it causes fluid particles to compress, which may lead to the formation of a shock (discontinuity). Then as the piston retracts, a forward-moving rarefaction, a smooth fan zone of continuously changing pressure, density, and velocity is generated. When the piston stops at the end of the cycle, another shock is sent forward into the medium. The variation in wave speed over the entire waveform is calculated by solving a Riemann problem. This study examined the interaction of shocks with a rarefaction. The flow field resulting from these interactions shows that the shock waves are attenuated to a Mach wave, and the pressure distribution within the flow field shows the initial wave is dissipated. The developed theory is applied to waves generated by 20 KHz, 500 KHz, and 2 MHz transducers with 50, 150, 500, and 1500 W power levels to explore the effect of frequency and power on the generation and decay of shock waves. This work enhances the understanding of the interactions of high-intensity ultrasonic waves with fluids.

show abstract

Section: Introductionmentioning

confidence: 99%

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Kewalramani

Zou²,

Marsh

et al. 2020

Acoustics

View full text Add to dashboard Cite

show abstract

“…Parametric acoustic arrays (PAA) were first introduced by Westervelt in 1963 [1]. Due to their high directivity and almost non-existent side lobes, many applications have been developed using PAA ranging from underwater applications [2,3], sediment exploration [4], communications [3,5,6], to medical applications [7]. In the last two decades, tremendous progress has been made in the field of PAAs in air to the point where there are multiple commercial solutions available for highly directive sound systems [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Idle Noise Reduction of a Parametric Acoustic Array Power Driver

Pirc

2019

Informacije MIDEM

View full text Add to dashboard Cite

Parametric acoustic arrays (PAA) have progressed from specialized niche applications to commercially available audio solutions in the last two decades. Their primary advantage is their incredible directivity and their main disadvantage is low conversion efficiency of the primary ultrasonic waves into audible sound. This paper presents a noise analysis of a practical implementation of a directional audio system. The system is comprised of a modulator, a D-class audio amplifier, and an emitter consisting of 97 commercially available piezoelectric ultrasonic transducers. The designed system exhibited an uncomfortable level of idle noise at the maximum volume level. The analysis of the signal path and all the noise sources revealed that the most critical component was the modulator, and a solution was devised which provided a 16 dB improvement of the carrier to noise ratio. Zmanjšanje lastnega šuma ojačevalnika in modulatorja za parametrično akustično poljeIzvleček: Parametrična akustična polja (PAP) so se v zadnjih dveh desetletjih razvila od specialnih nišnih aplikacij do komercialno dostopnih avdio sistemov. Njihova poglavitna prednost je izredna usmerjenost zvoka, glavna slabost pa nizka učinkovitost pretvorbe primarnega ultrazvočnega valovanja v slišni zvok. V tem prispevku je predstavljena analiza šuma praktične realizacije usmerjenega avdio sistema. Sistem sestavljajo modulator, avdio ojačevalnik razreda D in ultrazvočni oddajnik, sestavljen iz sedemindevetdesetih komercialno dostopnih piezoelektričnih ultrazvočnih pretvornikov. Zasnovani sistem je pri maksimalni nastavitvi glasnosti oddajal neprijetno visok nivo lastnega šuma. Analiza signalne poti in vseh možnih virov šuma je pokazala, da je najbolj kritična komponenta analogni množilnik. Na podlagi analize smo zasnovali rešitev, ki je izboljšala razmerje med velikostjo nosilca in šuma za 16 dB.

show abstract

“…Although lab on a chip microfluidic processes have begun to revolutionise experimental procedures in the medical lab environment, the application of micro-channel and standing wave [13] research within the human body is limited due to the fundamental non-linearity of our bodies, biological materials and the high acoustic scattering caused within the body [14]. Hence, an in-depth analysis and characterisation of high frequency acoustic excitation devicesspecifically ultrasonic transducersmust be completed, along with the supporting fundamental wave theory [12].…”

Section: Acoustofluidicsmentioning

confidence: 99%

“…This near field regime in fluids is fundamentally non-linear, due to the loss of energy in secondary wave forms via dissipation due to fluid viscosity, heat conductivity, fluid relaxation processes and the non-linearity in the formation of higher wave harmonics [14]. These two factors counteract each other in the generation and damping of secondary wave forms and change the wave shape as it propagates through the medium [14].…”

Section: Near Field and Far Field Regimesmentioning

confidence: 99%

“…Two important areas of far field wave analysis are the sinusoidal standing wave pressure field [23] and the pulse generated traveling wave equation [22]. However, due to the nonlinearity, high biological material attenuation and high acoustic scattering within the body [14], the application of stranding wave theory is not appropriate under the research area defined.…”

Section: Traveling Wave Pressure Fieldsmentioning

confidence: 99%

See 1 more Smart Citation

UQ eSpace

Hensel¹

View full text Add to dashboard Cite

Introduction to nonlinear acoustics

Cited by 32 publications

References 6 publications

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Idle Noise Reduction of a Parametric Acoustic Array Power Driver

UQ eSpace

Contact Info

Product

Resources

About