S.L. Firebaugh, F. Roignant, and E.A. Terray
United States Naval Academy, Annapolis, Maryland, USA
Polytechnique Nantes, Nantes, France
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
A fast, high-sensitivity detector is required for studies of environmentally relevant gases. Photoacoustic spectroscopy (PAS), an absorption spectroscopy technique in which absorption is detected as sound, is explored as a possible solution. A tuning-fork based PAS sensor is modeled using COMSOL. The model combines the acoustic and piezoelectric modules and also includes viscous damping. The ...
L. Martinelli, and A. Lamberti
Universita di Bologna, Italy
Objective of this contribution is to show how to implement the Mild Slope Equations with COMSOL Multiphysics. These equations are commonly used to study the propagation of waves in harbors. Some interesting features are presented, namely the use of weak terms (used for the modelling of the source term); the evaluation of a smooth phase gradient from the complex dependent variable; a robust ...
V. Romero-García, A. Krynkin, J.V. Sánchez-Pérez, S. Castiñeira-Ibáñez, and L.M. Garcia-Raffi
Centro de Tecnologías Físicas Acústica, Universidad Politécnica de Valencia, Valencia, Spain
School of Computing, Science & Engineering, University of Salford, Salford, United Kingdom
Depto. Física Aplicada, Universidad Politécnica de Valencia, Valencia, Spain
Instituto Universitario de Matemática Pura y Aplicada, Universidad Politécnica de Valencia, Valencia, Spain
The elastic and geometrical properties of Low Density Polyethylene (LDPE) foam are used in this paper to improve the attenuation properties of periodic arrangements of acoustic scatterers known as Sonic Crystals (SCs). A specific recycled profile of LDPE foam is used as elastic-acoustic scatterer. The acoustic spectrum of the single scatterer shows two attenuation peaks in the low frequency ...
Y. Jing, and N. Xiang
Graduate program of Architectural Acoustics, School of Architecture, Rensselaer Polytechnic Institute, Troy, NY, USA
This note proposes a modified boundary condition for the diffusion equation model to predict the reverberation times and sound pressure distributions in enclosures.While previous diffusion equation models usually only have good performances for a certain range of absorption surfaces, the modified diffusion model yields more satisfactory results for both low and high absorption surfaces.An example ...
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 ...
G. Rosi, L. Teresi, A. DiCarlo, and F. dell'Isola
LaMS - Università degli Studi Roma Tre, Roma, Italy
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 ...
M. Swamy, L. J. van Lier, J. Smeulers
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 ...
M. Yeoman, V. Sivasailam, A. Tomar
Continuum Blue Ltd., Ystrad Mynach, UK
Jaguar Land Rover Ltd, Coventry, UK
The design of windows and or other perforated structures which allow the free flow of air into & out of a building or system, while being fully soundproofed or attenuate certain frequencies is of great interest to architects and design engineers, where sound as a longitudinal wave, is difficult to separate it from its medium of propagation. In this work, we present the analysis of air ...
M. Weber, T. Kletschkowski, and B. Samtleben
Helmut-Schmidt-University Hamburg, 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 ...
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 ...