Technical Papers and Presentations

Here you will find presentations given at COMSOL Conferences around the globe. The presentations explore the innovative research and products designed by your peers using COMSOL Multiphysics. Research topics span a wide array of industries and application areas, including the electrical, mechanical, fluid, and chemical disciplines. Use the Quick Search to find presentations pertaining to your application area.

Temperature Gradients Controlled Broadband Acoustic Omnidirectional Absorber

F. Qian[1], L. Quan[1], X. Liu[1]
[1]Institute of Acoustics and School of Physics, Nanjing University, Nanjing, China

Previous research into acoustic omnidirectional absorber (AOA) has shown the feasibility of forming acoustic black hole to guide the incident wave into the central absorptive cavity. However, major restrictions to practical applications exist due to complexity of designing metamaterials and unchangeable working states. Here, we propose two cylindrical, two-dimensional AOA schemes based on ...

Identification of Noise Sources by Means of Inverse Finite Element Method

M. Weber[1], T. Kletschkowski[1], and B. Samtleben[2]
[1]Helmut-Schmidt-University Hamburg, Germany
[2]Airbus Germany

An inverse finite element method for noise source identification in an aircraft cabin is presented. If all sound sources are located on the boundary of the cabin, the equation system resulting from a matching FE model can be re-sorted in such a way that computation of the unknown boundary data is possible from measurement data taken in the cavity. The method is first validated using a simplified ...

A Study of Seismic Robot Actuation Using COMSOL Multiphysics

S.L. Firebaugh, E.A. Leckie, J.A. Piepmeier, and J.A. Burkhardt
United States Naval Academy, Annapolis, Maryland, USA

Microrobotics has promising applications in microsurgery and microassembly. A challenge in these systems is interfacing with the robot. This project explores crawling robots that are powered and controlled through a global mechanical vibration field. By controlling the frequencies present in the vibration field, the user can then steer the robot. The “robot” has a rectangular body with ...

Electro-acoustic Coupling in Nematic Liquid Crystals

G. Rosi[1], L. Teresi[1], A. DiCarlo[1], and F. dell'Isola[2]
[1]LaMS - Università degli Studi Roma Tre, Roma, Italy
[2]Università degli Studi di Roma "La Sapienza", Roma, Italy

Liquid crystals - as all liquids - are generally modelled as incompressible media. In fact, mass-density changes occurring in these mesophases are minuscule and inconsequential in most regimes of interest. However, liquid crystals exhibit also phenomena that call for a more refined theory. In particular, it is experimentally well established that the Fréedericksz transition - i.e., the sudden ...

Optimization of Acoustic Silencer for the Screw Compressor System

M. Swamy[1], L. J. van Lier[1], J. Smeulers[1]
[1]TNO, Delft, The Netherlands

In one of the screw compressor system, designed silencer was not optimal. A great challenge was the large variation in operating conditions, especially the variation of the molecular weight of the gas. There was need to optimize the silencer. This paper describes the acoustic modelling tools to optimize the acoustic performance of the silencer. Optimization steps carried out are based on the ...

Application of a Weakly Non-Linear Analysis to the Analysis of Thermoacoustic Combustion Instabilities

D. Laera[1], S. M. Camporeale[1], G. Campa[2]
[1]Politecnico di Bari, Bari, Italy
[2]Ansaldo Energia, Genoa, Italy

The thermoacoustic combustion instabilities are complex phenomena that may occur in steady flow combustion systems that are aboard of, e.g., rocket engines or gas turbines. The phenomena involve the interaction of chemical reactions with fluid-dynamic and propagation of pressure waves in the combustion chamber. Combustion instabilities may lead to a stable condition (known as “limit-cycle”) ...

Finite-element modeling of acoustic scattering from 3-D elastic structures

David S. Burnett
Naval Surface Warfare Center
Panama City, USA

The author is integrating a suite of software tools for modeling the scattering of acoustic beams (sonar) from undersea targets (mines) that may be buried or partially buried in the sedimentary ocean bottom in littoral (shallow water) environments. This is a Multiphysics problem involving acoustic waves in the water, acoustic or poro-elastic waves in the sediment, and both elastic and acoustic ...

Application of COMSOL to Acoustic Imaging

K. Mcilhany, and J.C Hernandez
U.S. Naval Academy, Annapolis, MD, USA

Acoustic Imaging of hand movement is being studied with COMSOL and Matlab. A hardware implementation is being pursued that will be an array of 16x16 ultra-sonic speakers placed in a grid facing a similar grid of 16x16 microphones, operating at 40kHz. COMSOL is used to repeatedly calculate the diffraction pattern from a small scattering center, approximately 1.0cm in diameter. In conjunction ...

Application of Transfer Matrix Method in Acoustics

G. Campa, and S.M. Camporeale
Politecnico di Bari, Bari, Italy

The Transfer Matrix method in the Acoustics Module of COMSOL Multiphysics is used when the whole system can be represented into a sequence of subsystems that interact only with adjacent subsystems. This method is frequently used in mathematics and, particularly, in acoustics. The application of the present method is really useful, because it permits to break the total system into a network of ...

Modelling the Wall Vibrations of Brass Wind Instruments

V. Chatziioannou, and W. Kausel
Institute of Music Acoustics
University of Music and Performing Arts
Vienna, Austria

The vibration of the walls of brass wind instruments has been a subject of study in the field of musical acoustics throughout the last decades. The amplitude of such vibrations, stimulated by the oscillating air pressure inside the instrument bore, is very small compared to the dimensions of the instrument. However, it has been recently shown that at the flaring regions of the bell of brass ...

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