Dinex Emission Technology A/S, Middelfart, Denmark
Exhaust noise must meet legislation targets, customer expectations and cost reduction which call for design optimization of the exhaust systems in the design phase. One solution is to use 3 dimensional linear pressure acoustics and calculate the transfer matrix of the muffler. The transfer matrix is the basis for calculating either the insertion loss or transmission loss of a muffler. The 3D ...
Simulation of a New PZT Energy Harvester with a Lower Resonance Frequency Using COMSOL Multiphysics® - new
H. Elbahr, T. Ali[1,2], A. Badawi, S. Sedky
Zewail City of Science and Technology - Cairo, Cairo, Egypt
Cairo University, Cairo, Egypt
Energy harvesting from environmental vibration nowadays is feasible because of natural oscillations like that caused by air or liquid flow and by exhalation or the heartbeat of a human body. This vibration frequency is typically low (in order of less than 1 kHz). Accordingly, low-frequency vibration based energy harvesting systems are an important research topic; these systems can be used for ...
郁殿龙 , 温激鸿 , 尹剑飞 ,
汽车、飞行器、舰船、高速列车等工程装备中，振动和噪声问题会严重影响装备可靠性、安全性、使用寿命和人员的健康。因此，减振降噪需求迫切，相关技术和研究也得到了前所未有的重视。 国防科技大学振动与噪声控制研究团队从2003年开始，致力于基于人工周期结构理论的弹性波传播特性、调控机理及其应用探索研究。将物理学领域中声子晶体、声学超材料等人工周期结构中的新概念与工程减振降噪应用相结合，设计研发了多种声波控制器件与结构。 COMSOL Multiphysics® 声学模块的丰富接口及其处理多物理场耦合问题的强大功能，为研究团队解决复杂多尺度结构的声振特性预报和减振降噪设计提供了有力的工具。在此平台上，研究团队设计了局域共振低频吸声材料，并依托学校“天河二号”超级计算机并行计算环境，开展了元胞尺度（mm量级）到部件尺度（m量级）模型的声学特性有限元建模求解 ...
T. Graf, T. Gisler, P. Sollberger, O. Schaelli
School of Engineering and Architecture, Lucerne University, Horw, Switzerland
Axisymmetric acoustic waves propagating along buried water pipes have been investigated by FEM and experimentally. Universal dispersion relations of the fundamental mode were obtained as a function of the standard dimension ratio SDR and of the material surrounding the pipe (soil, air). At low frequency there exists little dispersion and the “dc” phase velocity of the leak noise is independent ...
D. Neihguk , A. Prasad ,
 Mahindra & Mahindra Ltd., Chennai, India
The acoustic performance of an acoustically short Concentric Tube Resonator (CTR) is investigated to find an optimum porosity for a given length to diameter ratio. The study is motivated by the following practical difficulties encountered in automotive exhaust noise control: 1. Increasing trend of downsized engine and increase in power to weight ratio of engine for better fuel economy. 2. The ...
H. Bruus, P.B. Muller, R. Barnkob, M.J.H. Jensen
Technical University of Denmark, Kongens Lyngby, Denmark
COMSOL, Kongens Lyngby, Denmark
We have simulated the ultrasound-induced acoustophoretic motion of microparticles suspended in an aqueous solution. The full first-order thermoviscous acoustics equations have been implented on a rectangular microfluidic 2D domain excited with an ultrasound field tuned to resonance near 2 MHz. The micrometer-thin but crucial viscous boundary layers at the rigid walls have been fully resolved. ...
R. Haettel, A. Daneryd, M. Kavasoglu, C. Ploetner
ABB Corporate Research, Västerås, Sweden
ABB Transformers, Varennes, QC, Canada
Today, low noise is a mandatory feature for power transformers to comply with customer specifications and environmental regulations. Therefore, it is crucial to develop sound prediction tools with sufficient accuracy to avoid overkill margins in design and costly modifications after transformer completion. The paper will focus on core noise which is a typical multiphysics phenomenon involving ...
R. C. Thiagarajan
ATOA Scientific Technologies Private Limited
Ultrasonic acoustic waves usually encounter interfaces with significant impedance mismatch in practical medical or industrial imaging applications. A transparent interface can help to improve the performance of medical and industrial imaging and overall innovative applications. Similarly, a broadband total reflection interface can help to improve the architectural or transportation barrier ...
Solving the Inverse Problem of Resonant Ultrasound Spectroscopy on Dumbbell-shaped Compression Samples Using COMSOL Multiphysics®
M. C. Golt
U.S. Army Research Laboratory*, Aberdeen Proving Ground, MD, USA
*Contracted through Dynamic Science, Inc.
The dumbbell geometry is an ideal shape for testing the compressive strength of advanced ceramic materials. This paper details the combined use of COMSOL Multiphysics® and LiveLink™ for MATLAB® for determining the elastic properties of dumbbell-shaped samples by measuring their acoustic resonance frequencies. Degenerate bending modes which are sensitive to inhomogeneities or machining defects ...
Simulation of Acoustic Energy Harvesting Using Piezoelectric Plates in a Quarter-Wavelength Straight-Tube Resonator
B. Li, J.H. You
Southern Methodist University, Dallas, TX, USA
An acoustic energy harvesting mechanism at low frequency (~200 Hz) using lead zirconate titanate (PZT) piezoelectric cantilever plates placed inside a quarter-wavelength straight-tube resonator has been studied using COMSOL Multiphysics 4.3 and compared with experimental data. When the tube resonator is excited by an incident wave at its acoustic eigenfrequency, an amplified acoustic resonant ...