Luke Bennetts

Luke Bennetts
University of Adelaide · School of Mathematical Sciences

PhD

About

113
Publications
17,163
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2,350
Citations

Publications

Publications (113)
Article
Extensions of Rayleigh–Bloch waves above the cutoff frequency are studied via the discrete spectrum of a transfer operator for a channel containing a single cylinder with quasi-periodic side-wall conditions. Above the cutoff, the Rayleigh–Bloch wavenumber becomes complex valued and an additional wavenumber appears. For small- to intermediate-radius...
Conference Paper
Full-text available
The problem of non-linear radiated waves generated by a submerged circular cylinder undergoing a forced heaving oscillation is studied. The Linear Potential Flow (LPF) theory approximation is used as a reference to the solution. A Computational Fluid Dynamics (CFD) commercial software FLOW-3D ® is used to simulate Euler approximation of Navier-Stok...
Preprint
A model of the extent of overwash into fields of sea ice is developed. The extent model builds on previous work modelling overwash of a single floe by regular waves to include irregular waves and many random floes. The extent model is validated against laboratory experiments. The model is used to study the the extent of overwash into fields of panc...
Article
Full-text available
Irregular, unidirectional surface water waves incident on model ice in an ice tank are used as a physical model of ocean surface wave interactions with sea ice. Results are given for an experiment consisting of three tests, starting with a continuous ice cover and in which the incident wave steepness increases between tests. The incident waves rang...
Preprint
Full-text available
Irregular, unidirectional surface water waves incident on model ice in an ice tank are used as a physical model of ocean surface wave interactions with sea ice. Results are given for an experiment consisting of three tests, starting with a continuous ice cover and in which the incident wave steepness increases between tests. The incident waves rang...
Preprint
Full-text available
Extensions of Rayleigh-Bloch waves above the cut-off frequency are studied via the discrete spectrum of a transfer operator for a generalised channel containing a single cylinder. Their wavenumbers are shown to become complex-valued and an additional pair of wavenumbers to appear. For small to intermediate radius values, the extended Rayleigh-Bloch...
Article
A solution method is developed for a linear model of ice shelf flexural vibrations in response to ocean waves, in which the ice shelf thickness and seabed beneath the ice shelf vary over distance, and the ice shelf/sub–ice-shelf cavity are connected to the open ocean. The method combines a decomposition of the ice shelf displacement profile at a pr...
Article
A physical model is discussed that mimics the interaction between ocean waves and a multitude of loose pancake ice floes, which form the outer edge of the Arctic and Antarctic marginal ice zones during winter sea ice formation. The pancakes were modeled by using ice cubes with different concentrations, while waves were generated mechanically. The i...
Article
Full-text available
The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air–sea interface and contribute to absorbing, storing, and releasing heat, moisture, gases, and momentum. Owing to its remoteness and harsh environment, this region is significantly undersample...
Preprint
Full-text available
Propagation of energetic surface gravity waves over a $>40$\,km transect of the winter Antarctic marginal ice zone comprised of pancake floes and interstitial frazil ice during an explosive polar cyclone are presented, obtained with a shipborne stereo-camera system. The waves are shown to attenuate at an exponential rate over distance, but, despite...
Preprint
Full-text available
A solution method is developed for a model of ice shelf vibrations in response to ocean waves, in which the ice shelf thickness and seabed beneath the ice shelf vary over distance, and the ice shelf/sub--ice--shelf cavity are connected to the open ocean. The method combines a decomposition of the ice shelf motion into free modes of vibration, a fin...
Article
Two- and three-dimensional models are proposed for ocean-wave attenuation due to scattering by ice floes in the marginal ice zone, in which the attenuation rate depends on the horizontal size of the individual floes. The scattering models are shown to reproduce the behaviour of wave attenuation over short wave periods. However, it is shown that sca...
Preprint
Full-text available
The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air-sea interface and contribute to absorbing, storing, and releasing heat, moisture, gasses, and momentum. Owing to its remoteness and harsh environment, this region is significantly under samp...
Conference Paper
Full-text available
Ocean waves penetrate hundreds of kilometres into the ice- covered ocean. Waves fracture the level ice into small floes, herd floes, introduce warm water and overwash the floes, accelerating ice melt and causing collisions, which concurrently erodes the floes and influences the large-scale deformation. Concomitantly, interactions between waves and...
Article
Full-text available
A mathematical model for predicting the vibrations of ice-shelves based on linear elasticity for the ice-shelf motion and potential flow for the fluid motion is developed. No simplifying assumptions such as the thinness of the ice-shelf or the shallowness of the fluid are made. The ice-shelf is modelled as a two-dimensional elastic body of an arbit...
Article
Water waves in natural environments are typically broadband, nonlinear, and dynamic phenomena. Taking concepts developed for slow light in optics, we address the challenge of designing arrays to control the spatial distribution of wave energy, and amplify specific frequencies from within target frequency bands at individual locations. Meter-scale w...
Article
Water wave transmission and energy dissipation by a floating plate in the presence of overwash - Volume 889 - Filippo Nelli, Luke G. Bennetts, David M. Skene, Alessandro Toffoli
Article
Full-text available
Plain Language Summary During the Antarctic winter, small pancake ice floes, which form rapidly in wavy conditions, dominate new ice growth and create a dynamic environment. However, there are only a handful of local observations of pancake ice drift, particularly during the intense polar cyclones that frequently reshape the ice cover. More observa...
Preprint
Water waves in natural environments are typically broadband, nonlinear and dynamic phenomena. Taking concepts developed for slow light in optics, we address the challenge of designing arrays to control the spatial distribution of wave energy, and amplify target frequencies at specified locations. Experiments on incident waves interacting with a chi...
Article
Energy amplification in square-lattice arrays of C-shaped low-frequency resonators, where the resonator radii are graded with distance, is investigated in the two-dimensional linear acoustics setting for both infinite (in one dimension) and finite arrays. Large amplifications of the incident energy are shown in certain array locations. The phenomen...
Article
Full-text available
This paper investigates how scientific information and expertise was provided to decision-makers for consideration in situations involving risk and uncertainty. Seven case studies from the earth sciences were used as a medium for this exposition: (1) the 2010–2011 Canterbury earthquake sequence in New Zealand, (2) agricultural farming-system develo...
Article
Full-text available
This paper synthesizes important elements from case studies presented in its companion paper (Quigley et al. in Environ Syst Decis, 2019, https://doi.org/10.1007/s10669-019-09728-0) to define mutual and distinct characteristics, and to develop a more holistic understanding of how earth science was used to support diverse examples of decision-making...
Preprint
Full-text available
High temporal resolution in--situ measurements of pancake ice drift are presented, from a pair of buoys deployed on floes in the Antarctic marginal ice zone during the winter sea ice expansion, over nine days in which the region was impacted by four polar cyclones. Concomitant measurements of wave-in-ice activity from the buoys is used to infer tha...
Article
Full-text available
Plain Language Summary The extent of Antarctic sea ice is characterized by large regional variations that are in stark contrast with the alarming decreasing trends found in the Arctic. This is partly due to the presence of severe weather events, like extratropical cyclones travelling through the Southern Ocean and reaching the marginal ice zone (MI...
Article
Full-text available
The solution to the problem of the vibration of an ice shelf of constant thickness is calculated using the eigenfunction matching method in water of finite depth, and accounting for the draught of the shelf.The eigenfunction matching solution is validated against a solution found using the finite element method. The finite-depth solution is careful...
Article
The effective mass of an acoustical metamaterial chain, which consists of a modified monatomic chain with a lightweight attached mass–link system, is derived and used to analyse its low-frequency vibration-isolation properties. The effective mass is expressed in terms of the resonant and anti-resonant frequencies of a basic element of the chain, an...
Conference Paper
Full-text available
With the increasing demand for Arctic Engineering purposes, Squire suggests current theories may have oversimplified the sea ice hydroelasticity, indicating the need to develop numerical models to obtain more realistic solutions. Numerical models have been reported capable of achieving a full coupling between waves and rigid floating ice. When an i...
Article
Full-text available
The size distribution of pancake ice floes is calculated from images acquired during a voyage to the Antarctic marginal ice zone in the winter expansion season. Results show that 50% of the sea ice area is made up of floes with diameters of 2.3–4m. The floe size distribution shows two distinct slopes on either side of the 2.3–4m range, neither of w...
Article
A structure capable of substantially amplifying water waves over a broad range of frequencies at selected locations is proposed. The structure consists of a small number of C-shaped cylinders in a line array, with the cylinder properties graded along the array. Using linear potential-flow theory, it is shown that the energy carried by a plane incid...
Article
Full-text available
The ability to analyse attenuation rates of individual wave fields along rough media using the effective wave field is investigated for the problem of a string with continuous, randomly varying properties. A clustering method is developed to approximate the continuous problem as a discrete problem, which provides insights into the relationship betw...
Article
Full-text available
Three-dimensional scattering of ocean surface waves in the marginal ice zone (MIZ) is determined in the time domain. The solution is found using spectral analysis of the linear operator for the Boltzmann equation. The method to calculate the scattering kernel that arises in the Boltzmann model from the single-floe solution is also presented along w...
Article
Full-text available
Hydroelastic interactions between regular water waves and floating freshwater ice are investigated using laboratory experiments for a range of incident wave periods and steepnesses. It is shown that only incident waves with sufficiently long period and large steepness break up the ice cover and that the extent of breakup increases with increasing p...
Article
Full-text available
The size distribution of pancake ice floes is calculated from images acquired during a voyage to the Antarctic marginal ice zone in the winter expansion season. Results show that 50% of the sea ice area is made up by floes with diameters 2.3–4m. The floe size distribution shows two distinct slopes on either side of the 2.3–4m range. It is conjectur...
Preprint
Full-text available
Hydroelastic interactions between regular water waves and floating freshwater ice are investigated using laboratory experiments for a range of incident wave periods and steepnesses. It is shown that only incident waves with sufficiently long period and large steepness break up the ice cover, and that the extent of breakup increases with increasing...
Article
Full-text available
The frequency-domain and time-domain response of a floating ice shelf to wave forcing are calculated using the finite element method. The boundary conditions at the front of the ice shelf, coupling it to the surrounding fluid, are written as a special non-local linear operator with forcing. This operator allows the computational domain to be restri...
Preprint
A structure capable of substantially amplifying water waves over a broad range of frequencies at selected locations is proposed. The structure consists of a small number of C-shaped cylinders arranged in a line array, with the cylinder properties graded along the array. Using linear potential-flow theory, it is shown that the energy carried by a pl...
Article
Full-text available
Understanding the causes of recent catastrophic ice shelf disintegrations is a crucial step towards improving coupled models of the Antarctic Ice Sheet and predicting its future state and contribution to sea-level rise. An overlooked climate-related causal factor is regional sea ice loss. Here we show that for the disintegration events observed (th...
Article
Full-text available
Analysis of field measurements of ocean surface wave activity in the marginal ice zone, from campaigns in the Arctic and Antarctic and over a range of different ice conditions, shows the wave attenuation rate with respect to distance has a power‐law dependence on frequency with order between two and four. With this backdrop, the attenuation–frequen...
Article
Full-text available
Water wave overwash of a step by small steepness, regular incident waves is analysed using a computational fluid dynamics (CFD) model and a mathematical model, in two spatial dimensions. The CFD model is based on the two-phase, incompressible Navier–Stokes equations, and the mathematical model is based on the coupled potential-flow and nonlinear sh...
Article
Collisions between two thin floating disks forced by regular water waves are studied for a range of wave amplitudes and lengths, using laboratory wave basin experiments and a mathematical model. Three collision regimes are identified from the experiments in terms of collision frequency and strength, and the collisions are shown to be caused by drif...
Poster
Full-text available
Laboratory wave basin experiments are implemented to investigate wave-driven collisions and rafting between ice floes. Collision and rafting regimes are identified over a range of incident wave conditions and floe-floe separations. Five types of collision and rafting behaviours were observed. The experiments allowed identification of the dominant p...
Conference Paper
The marginal ice zone (MIZ) is the outer part of the sea-ice covered ocean, where ice can be found in the form of large floating chucks better known as floes. Since it is the area where the most part of the interaction between ice cover and ocean waves takes place, it requires careful modelling. However existing mathematical models, based on the tr...
Article
Full-text available
On the calculation of normal modes of a coupled ice-shelf/sub-ice-shelf cavity system - Volume 63 Issue 240 - MICHAEL H. MEYLAN, LUKE G. BENNETTS, ROGER J. HOSKING, ELLIOT CATT
Conference Paper
Full-text available
Waves penetrate deep into the ice covered seas, inducing breakup of the ice cover. Concomitantly, the ice cover attenuates the wave energy over distance, so that wave impacts die out eventually. Observations of wave attenuation and concurrent wave-induced breakup in the literature are serendipitous due to difficulties in making measurements in ice...
Article
Full-text available
Impacts of wave-induced breakup of Antarctic sea ice on ice concentration and volume are investigated using a modified version of the CICE sea-ice model, run in stand-alone mode from 1979–2010. Model outputs show that during summer wave-induced breakup reduces local ice concentration by up to 0.3–0.4 in a vicinity of the ice edge and total ice volu...
Conference Paper
Full-text available
Ocean waves are a huge resource of renewable energy. Wave energy converter (WEC) devices are being developed to optimise capture of this energy. A point absorber (PA), whose dimensions are much smaller than a wavelength, is a typical type of WEC with the main advantage being its insensitivity to wave direction. Examples of operational PA devices ar...
Article
Linear potential-flow theory is used to study loads imposed on finite line arrays of rigid, bottom-mounted, surface-piercing, vertical cylinders by surface water waves. Perturbations in the cylinder locations are shown to damp the resonant loads experienced by the unperturbed array. A relationship is established between the damping and the phenomen...
Article
Full-text available
https://theconversation.com/listen-up-a-plan-to-help-scientists-get-their-research-heard-by-decision-makers-71627 Many scientists are keen to communicate research they believe can help inform the decisions people make, from public opinion to the policy of our governments. But the will of scientists to abandon intellectual “ivory towers” does not i...
Article
Full-text available
Impacts of wave-induced breakup of Antarctic sea ice on ice concentration and volume are investigated using a modified version of the CICE sea ice model, run in standalone mode from 1979–2010. Model outputs show that breakup reduces ice concentration by up to 0.3–0.4 in a vicinity of the ice edge during the summer, and total ice volume by over 500...
Article
Full-text available
Measurements of the wave fields reflected and transmitted by a thin floating plastic plate are reported for regular incident waves over a range of incident periods (producing wavelengths comparable to the plate length) and steepnesses (ranging from mild to storm-like). Two different plastics are tested, with different densities and mechanical prope...
Article
Two methods for computing the complex-valued effective wavenumber of a rough beam in the context of linear time-harmonic theory are presented. The roughness of the beam is modelled as a continuous random process of known characteristic length and root-mean-square amplitude for either the beam mass or the beam rigidity. The first method is based on...
Article
Full-text available
An eigenfunction-matching method is developed for the problem of linear water-wave scattering by a circular floating porous elastic plate, and a coupled boundary-element and finite-element method is developed for the problem in which the plate is of arbitrary shape. The methods are shown to produce the same solutions for a circular plate, and their...
Article
A theoretical model is used to study wave energy attenuation and directional spreading of ocean wave spectra in the marginal ice zone (MIZ). The MIZ is constructed as an array of tens of thousands of compliant circular ice floes, with randomly selected positions and radii determined by an empirical floe size distribution. Linear potential flow and...