THE RADIATION FORCE ON A SPHERICAL OBSTACLE IN A CYLINDRICAL SOUND FIELD

1956 ◽  
Vol 34 (3) ◽  
pp. 276-287 ◽  
Author(s):  
T. F. W. Embleton
Keyword(s):  
General Expression ◽  
Spherical Harmonics ◽  
Sound Field ◽  
Radiation Force ◽  
Cylindrical Wave ◽  
Lower Degree ◽  
Zero Force ◽  
Spherical Waves ◽  
Radiation Forces

The corresponding problems of the radiation forces acting on a spherical obstacle in a plane or spherical progressive sound field have been examined previously by King (Proc. Roy. Soc. (London), A, 147:212.1934) and Embleton (J. Acoust. Soc. Amer. 26:40. 1954) respectively. In these cases the sound field and scattering obstacle both have symmetry of revolution about the line joining the center of the obstacle to the origin of the sound field, but for a cylindrical sound field there exists only a much lower degree of symmetry. A general expression has been obtained for the radiation force in terms of the complex amplitudes of spherical harmonics required to synthesize the incident sound field—for the cases of greatest symmetry this reduces to the simpler expression previously obtained. The first 20 non-zero amplitudes have been evaluated for a cylindrical sound field and it is shown that the force is one of attraction near to the source, becomes zero at a certain distance, and is a force of repulsion at a greater distance. Qualitatively, this force is the same as for spherical waves but for any size of obstacle and frequency of the sound field the point of zero force is always nearer to the source in a cylindrical wave.

Applications of Ultrasonic Radiation Forces

2011 ◽  
Vol 215 ◽  
pp. 259-262 ◽  
Author(s):  
Z.W. Wang ◽  
G.Q. Pan ◽  
Dong Hui Wen
Keyword(s):  
Mechanical System ◽  
Sound Field ◽  
Radiation Force ◽  
Acoustic Levitation ◽  
Ultrasonic Machining ◽  
Ultrasonic Radiation ◽  
Keynote Paper ◽  
Radiation Forces

This keynote paper aims at introducing applications of ultrasonic radiation force in industry. The chosen focus is to understand how to use it. Since the phenomenon of acoustic levitation can reflect the exciting of ultrasonic radiation force directly. The paper starts with an analysis on the tungsten ball floating on a sound field and ultrasonic micro-manipulation study in micro Electronic Mechanical System (MEMS). And ultrasound has been successfully used to degrade wastewater as its cavitation. At the same time, different kinds of micro-ultrasonic machining were used to show how exciting machining and ultrasonic radiation combined. A view from the authors and the final Conclusions show future applications of ultrasonic radiation force.

scholarly journals Mathematical modeling and experimental study on solid–liquid suspension separation in ultrasonic standing wave field

2021 ◽  
pp. 146134842110229
Author(s):  
Yajing Wang ◽  
Liqun Wu ◽  
Yaxing Wang ◽  
Yafei Fan
Keyword(s):  
Standing Wave ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Sound Field ◽  
Radiation Force ◽  
High Energy ◽  
Factors Affecting ◽  
Liquid Suspension ◽  
Ultrasonic Standing Wave ◽  
Solid Liquid

A new method of removing waste chips is proposed by focusing on the key factors affecting the processing quality and efficiency of high energy beams. Firstly, a mathematical model has been established to provide the theoretical basis for the separation of solid–liquid suspension under ultrasonic standing wave. Secondly, the distribution of sound field with and without droplet has been simulated. Thirdly, the deformation and movement of droplets are simulated and tested. It is found that the sound pressure around the droplet is greater than the sound pressure in the droplet, which can promote the separation of droplets and provide theoretical support for the ultrasonic suspension separation of droplet; under the interaction of acoustic radiation force, surface tension, adhesion, and static pressure, the droplet is deformed so that the gas fluid around the droplet is concentrated in the center to achieve droplet separation, and the droplet just as a flat ball with a central sag is stably suspended in the acoustic wave node.

Radiation modes of propeller tonal noise

2021 ◽  
pp. 1-25
Author(s):  
Hanbo Jiang ◽  
Siyang Zhong ◽  
Han Wu ◽  
Xin Zhang ◽  
Xun Huang ◽  
...  
Keyword(s):  
Spherical Harmonics ◽  
Sound Field ◽  
Low Noise ◽  
Noise Model ◽  
Sound Waves ◽  
Tonal Noise ◽  
Noise Sources ◽  
Separate Source ◽  
Radial Forces ◽  
Flow Variables

Abstract This paper focuses on the radiation modes and efficiency of propeller tonal noise. The thickness noise and loading noise model of propellers has been formulated in spherical coordinates, thereby simplifying numerical evaluation of the integral noise source. More importantly, the radiation field can be decomposed and projected to spherical harmonics, which can separate source-observer positions and enable an analysis of sound field structures. Thanks to the parity of spherical harmonics, the proposed model can mathematically explain the fact that thrusts only produce antisymmetric sound waves with respect to the rotating plane. In addition, the symmetric components of the noise field can be attributed to the thickness, as well as drags and radial forces acting on the propeller surface. The radiation efficiency of each mode decays rapidly as noise sources approach the rotating centre, suggesting the radial distribution of aerodynamic loadings should be carefully designed for low-noise propellers. The noise prediction model has been successfully applied to a drone propeller and achieved a reliable agreement with experimental measurements. The flow variables employed as an input of the noise computation were obtained with computational fluid dynamics (CFD), and the experimental data were measured in an anechoic chamber.

Numerical Investigation of Parametric Rolling of a Container Ship in Regular and Irregular Waves

2017 ◽  
Author(s):  
Suresh Rajendran ◽  
C. Guedes Soares
Keyword(s):  
Incident Wave ◽  
Radiation Force ◽  
Wave Profile ◽  
Irregular Waves ◽  
Container Ship ◽  
Hydrodynamic Coefficients ◽  
Parametric Rolling ◽  
Nonlinear Radiation ◽  
Strip Theory ◽  
Radiation Forces

Parametric rolling of a post-Panamax C11 class containership in regular and irregular waves is numerically investigated using body nonlinear time domain methods based on strip theory. The Froude-Krylov and the hydrostatic forces are calculated for the exact wetted surface area under the undisturbed incident wave profile. Two kinds of formulations are used for calculation of the radiation forces. The first one employs a linear radiation force in which the frequency dependent hydrodynamic coefficients are calculated for mean position of the sections at mean water level. The second formulation calculates the hydrodynamic coefficients for the exact submerged depth of ship sections under the undisturbed incident wave profile, and hence called as body nonlinear radiation force. The numerical results from the aforementioned formulations are compared with each other, and also with experimental results obtained from a wave tank in both regular and irregular waves. For all the cases in regular waves, the vulnerability to parametric rolling is clearly identified by the numerical models, even though a few discrepancies are observed in the estimation of the severity (maximum roll angle) of the problem. In this paper, the effects of the linear and body nonlinear radiation forces on the numerical calculation of parametric rolling of a container ship and the ability of the numerical methods to identify parametric rolling are investigated.

Performance and Robustness Improvements in Ultrasonic Transportation Against Large-Scale Streaming

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Kun Jia ◽  
Ke-ji Yang ◽  
Bing-Feng Ju
Keyword(s):  
Elastic Constant ◽  
Lead Zirconate Titanate ◽  
Large Scale ◽  
Acoustic Radiation ◽  
Plane Waves ◽  
Acoustic Streaming ◽  
Sound Field ◽  
Radiation Force ◽  
Lead Zirconate ◽  
Potential Well

Acoustic streaming generated from the traveling-wave component of a synthesized sound field often has considerable influence on ultrasonic manipulations, in which the behavior of microparticles may be disturbed. In this work, the large-scale streaming pattern in a chamber with three incident plane waves is simulated, illustrating a directional traveling stream pattern and several vortical structures. Based on the numerical results, the trapping capability of an acoustic potential well is quantitatively characterized according to several evaluation criteria: the boundary and elastic constant of the acoustic potential well, the acoustic radiation force offset ratio, and the elastic constant offset ratio. By optimizing these parameters, the constraint of the acoustic potential well can be strengthened to promote the performance and robustness of the ultrasonic transportation. An ultrasonic manipulation device employing three 1.67-MHz lead zirconate titanate (PZT) transducers with rectangular radiation surface is prototyped and performance tested. The experimental results show that the average fluctuations of a microparticle during transportation have been suppressed into a region less than 0.01 times the wavelength. Particle displacement from equilibrium is no longer observed.

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