Interpolation of Hilbert and Sobolev spaces: quantitative estimates and counterexamples

SN Chandler-Wilde, DP Hewett, A Moiola - Mathematika, 2015 - cambridge.org
This paper provides an overview of interpolation of Banach and Hilbert spaces, with a focus
on establishing when equivalence of norms is in fact equality of norms in the key results of …

Is the Helmholtz equation really sign-indefinite?

A Moiola, EA Spence - Siam Review, 2014 - SIAM
The usual variational (or weak) formulations of the Helmholtz equation are sign-indefinite in
the sense that the bilinear forms cannot be bounded below by a positive multiple of the …

Sobolev Spaces on Non-Lipschitz Subsets of with Application to Boundary Integral Equations on Fractal Screens

SN Chandler-Wilde, DP Hewett, A Moiola - Integral Equations and …, 2017 - Springer
We study properties of the classical fractional Sobolev spaces on non-Lipschitz subsets of
R^ n R n. We investigate the extent to which the properties of these spaces, and the relations …

A frequency-independent boundary element method for scattering by two-dimensional screens and apertures

DP Hewett, S Langdon… - IMA Journal of …, 2015 - academic.oup.com
We propose and analyse a hybrid numerical–asymptotic boundary element method (BEM)
for time-harmonic scattering of an incident plane wave by an arbitrary collinear array of …

A fast and well-conditioned spectral method for singular integral equations

RM Slevinsky, S Olver - Journal of Computational Physics, 2017 - Elsevier
We develop a spectral method for solving univariate singular integral equations over unions
of intervals by utilizing Chebyshev and ultraspherical polynomials to reformulate the …

Well-posed PDE and integral equation formulations for scattering by fractal screens

SN Chandler-Wilde, DP Hewett - SIAM Journal on Mathematical Analysis, 2018 - SIAM
We consider time-harmonic acoustic scattering by planar sound-soft (Dirichlet) and sound-
hard (Neumann) screens embedded in R^n for n= 2 or 3. In contrast to previous studies in …

Wavenumber-explicit continuity and coercivity estimates in acoustic scattering by planar screens

SN Chandler-Wilde, DP Hewett - Integral Equations and Operator Theory, 2015 - Springer
We study the classical first-kind boundary integral equation reformulations of time-harmonic
acoustic scattering by planar sound-soft (Dirichlet) and sound-hard (Neumann) screens. We …

On the maximal Sobolev regularity of distributions supported by subsets of Euclidean space

DP Hewett, A Moiola - Analysis and Applications, 2017 - World Scientific
This paper concerns the following question: given a subset E of ℝ n with empty interior and
an integrability parameter 1< p<∞, what is the maximal regularity s∈ ℝ for which there …

Acoustic scattering by impedance screens/cracks with fractal boundary: well-posedness analysis and boundary element approximation

J Bannister, A Gibbs, DP Hewett - Mathematical Models and …, 2022 - World Scientific
We study time-harmonic scattering in ℝ n (n= 2, 3) by a planar screen (a “crack” in the
context of linear elasticity), assumed to be a non-empty bounded relatively open subset Γ of …

Acoustic scattering: high frequency boundary element methods and unified transform methods

SN Chandler-Wilde, S Langdon - arXiv preprint arXiv:1410.6137, 2014 - arxiv.org
We describe some recent advances in the numerical solution of acoustic scattering
problems. A major focus of the paper is the efficient solution of high frequency scattering …