http://ieeexplore.ieee.org/iel5/5/31047/01444179.pdf

Fundamentals of acoustics

: Documentation is given for some subroutines which compute potentials and other functions. A set of subroutines uses rational approximations to compute Bessel functions of integral order. One subroutine uses the Debye approximation for the efficient computation of Bessel functions of complex argument and complex order. Empirical formulae have been developed to express the limiting boundaries of the modes of computation. (Author)

/pdf/computation-of-special-functions-m37di5noj9.pdf

Computation of Special Functions

Active times for acoustic metamaterials

The boundary element method (BEM) in the context of acoustics or Helmholtz problems is reviewed in this paper. The basis of the BEM is initially developed for Laplace’s equation. The boundary integral equation formulations for the standard interior and exterior acoustic problems are stated and the boundary element methods are derived through collocation. It is shown how interior modal analysis can be carried out via the boundary element method. Further extensions in the BEM in acoustics are also reviewed, including half-space problems and modelling the acoustic field surrounding thin screens. Current research in linking the boundary element method to other methods in order to solve coupled vibro-acoustic and aero-acoustic problems and methods for solving inverse problems via the BEM are surveyed. Applications of the BEM in each area of acoustics are referenced. The computational complexity of the problem is considered and methods for improving its general efficiency are reviewed. The significant maintenance issues of the standard exterior acoustic solution are considered, in particular the weighting parameter in combined formulations such as Burton and Miller’s equation. The commonality of the integral operators across formulations and hence the potential for development of a software library approach is emphasised.

The Boundary Element Method in Acoustics: A Survey

Systematic design and realization of double-negative acoustic metamaterials by topology optimization

V. M. G.-C. and J. S.-D. acknowledge the support from the Spanish Ministerio de Economia y Competitividad (MINECO), and the European Union Fondo Europeo de Desarrollo Regional (FEDER) through Project No. TEC 2014-53088-C3-1-R.

/pdf/viscothermal-losses-in-double-negative-acoustic-4cuov696rf.pdf

Viscothermal Losses in Double-Negative Acoustic Metamaterials

OpenBEM is a collection of open source programs for solving the Helmholtz Equation using the Boundary Element Method. The collection is written in Matlab by the authors and contains codes for dealing with exterior and interior problems in two or three dimensions as well as implementation of axi-symmetric and half-space problems. It also contains a number of improvements such a dealing with thin objects and close surfaces, meshing for 2D and axisymmetrical problems, analytical solutions for verification, and a number of additional functions. This paper gives an overview of the capabilities of the program with examples of its use. Previous research results where OpenBEM was employed will be mentioned.

/pdf/openbem-an-open-source-boundary-element-method-software-in-1f3m4i305l.pdf

OpenBEM - An open source Boundary Element Method software in Acoustics

In recent years, boundary element method (BEM) and finite element method (FEM) implementations of acoustics in fluids with viscous and thermal losses have been developed. They are based on the linearized Navier–Stokes equations with no flow. In this paper, such models with acoustic losses are applied to an acoustic metamaterial. Metamaterials are structures formed by smaller, usually periodic, units showing remarkable physical properties when observed as a whole. Acoustic losses are relevant in metamaterials in the millimeter scale. In addition, their geometry is intricate and challenging for numerical implementation. The results are compared with existing measurements.

https://orbit.dtu.dk/files/127955850/1_1750006.pdf

A numerical model of an acoustic metamaterial using the boundary element method including viscous and thermal losses

/pdf/numerical-transducer-modeling-ys05ze2ccm.pdf

Vicente Cutanda Henriquez

Papers

Viscothermal Losses in Double-Negative Acoustic Metamaterials

OpenBEM - An open source Boundary Element Method software in Acoustics

A numerical model of an acoustic metamaterial using the boundary element method including viscous and thermal losses

Numerical Transducer Modeling

Shape optimization of micro-acoustic devices including viscous and thermal losses