scholarly journals Sound Scattering by a Flexible Plate Embedded on Free Surface

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Eldad J. Avital ◽  
Theodosios Korakianitis ◽  
Touvia Miloh
Keyword(s):  
Finite Difference ◽  
Sound Wave ◽  
Sound Field ◽  
Scattered Wave ◽  
External Pressure ◽  
Flexible Plate ◽  
Sound Scattering ◽  
Sound Structure ◽  
Structure Solution ◽  
Finite Difference Solution

Sound wave scattering by a flexible plate embedded on water surface is considered. Linear acoustics and plate elasticity are assumed. The aim is to assess the effect of the plate’s flexibility on sound scattering and the potential in using that flexibility for this purpose. A combined sound-structure solution is used, which is based on a Fourier transform of the sound field and a finite-difference numerical-solution of the plate’s dynamics. The solution is implemented for a circular plate subject to a perpendicular incoming monochromatic sound wave. A very good agreement is achieved with a finite-difference solution of the sound field. It is shown that the flexibility of the plate dampens its scattered sound wave regardless of the type of the plate’s edge support. A hole in the plate is shown to further scatter the sound wave to form maxima in the near sound field. It is suggested that applying an external oscillatory pressure on the plate can reduce significantly and even eliminate its scattered wave, thus making the plate close to acoustically invisible. A uniformly distributed external pressure is found capable of achieving that aim as long as the plate is free edged or is not highly acoustically noncompact.

Interaction between Strong Sound Waves and Cloud Droplets: Theoretical Analysis

2021 ◽  
Author(s):  
Ying-Hui Jia ◽  
Fang-Fang Li ◽  
Kun Fang ◽  
Guang-Qian Wang ◽  
Jun Qiu
Keyword(s):  
Sound Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Field ◽  
Pressure Level ◽  
Velocity Variation ◽  
Time Range ◽  
Sound Waves ◽  
Cloud Droplets ◽  
Acoustic Frequency

AbstractRecently strong sound wave was proposed to enhance precipitation. The theoretical basis of this proposal has not been effectively studied either experimentally or theoretically. Based on the microscopic parameters of atmospheric cloud physics, this paper solved the complex nonlinear differential equation to show the movement characteristics of cloud droplets under the action of sound waves. The motion process of individual cloud droplet in a cloud layer in the acoustic field is discussed as well as the relative motion between two cloud droplets. The effects of different particle sizes and sound field characteristics on particle motion and collision are studied to analyze the dynamic effects of thunder-level sound waves on cloud droplets. The amplitude of velocity variation has positive correlation with Sound Pressure Level (SPL) and negative correlation with the frequency of the surrounding sound field. Under the action of low-frequency sound waves with sufficient intensity, individual cloud droplets could be forced to oscillate significantly. The droplet smaller than 40μm can be easily driven by sound waves of 50 Hz and 123.4 dB. The calculation of the collision process of two droplets reveals that the disorder of motion for polydisperse droplets is intensified, resulting in the broadening of the collision time range and spatial range. When the acoustic frequency is less than 100Hz (@ 123.4dB) or the Sound Pressure Level (SPL) is greater than 117.4dB (@ 50Hz), the sound wave can affect the collision of cloud droplets significantly. This study provides theoretical perspective of acoustic effect to the microphysics of atmospheric clouds.

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

Lightweight Research of Automobile Dash Panel Based on Sound-Structure Sensitivity

2013 ◽  
Vol 681 ◽  
pp. 200-203 ◽  
Author(s):  
Lei Zhang ◽  
Zhi Yong Hao
Keyword(s):  
Sound Pressure ◽  
Lightweight Design ◽  
Sound Field ◽  
Coupling Model ◽  
Structure Sensitivity ◽  
Car Body ◽  
Field Coupling ◽  
Sound Structure ◽  
Dash Panel

In the research of the automobile front dash, the key of design is that acoustic need should be satisfied while losing the weight. In this paper, a structure-sound field coupling model of car body space is built. To fulfill the request, the dash panel is divided into several parts, and the sensitivity of thickness of each parts to the sound at the position of driver’s and co-pilot’s ears is calculated. Based on the sensitivity, the driver’s and the co-pilot’s parotic sound pressure is optimized while reducing the weight of front dash. The result proves that lightweight design is successful, which gives the reference to the design of the car body panels.

scholarly journals A Finite-Difference Wavenumber-Time Domain Method for Sound Field Prediction in a Uniformly Moving Medium

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bichun Dong ◽  
Runmei Zhang ◽  
Chuanyang Yu ◽  
Huan Li
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Sound Pressure ◽  
Sound Field ◽  
Time Domain Method ◽  
Practical Significance ◽  
Moving Medium ◽  
Domain Method ◽  
Aero Engines ◽  
The Stability

Sound field prediction has practical significance in the control of noise generated by sources in a flow, for example, the noise in aero-engines and ventilation systems. Aiming at accurate and flexible prediction of time-dependent sound field, a finite-difference wavenumber-time domain method for sound field prediction in a uniformly moving medium is proposed. The method is based on the second-order convective wave equation, and the wavenumber-time domain representation of the sound pressure field on one plane is forward propagated via a derived recursive expression. In this paper, the recursive expression is first deduced, and then numerical stability and dispersion of the proposed method are analyzed, based on which the stability condition is given and the correction of dispersion related to the transition frequency is made. Numerical simulations are conducted to test the performance of the proposed method, and the results show that the method is valid and robust at different Mach numbers.

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