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The global demand for energy shows no sign of slowing. Across the world, nations are using power in ever-expanding quantities and in new sectors, such as the widespread electrification of [...]

Abstract: This article describes a two-dimensional finite difference method for the numerical simulation of fully non-linear irrotational water waves. The computational domain is discretised in an Eulerian fashion using hierarchical Cartesian meshes, whilst the free surface location is explicitly tracked using a Lagrangian approach. The accuracy of the method is strongly dependent on the quality of the approximation to the free surface velocities and a novel method to compute these is proposed. A multigrid strategy is implemented to take advantage of the hierarchical nature of the grids, incorporating an efficient technique to generate the coarser grids. The method is verified through simulations of quasi-linear low-amplitude waves and through a comparative study using an asymmetric sloshing wave. The non-linear behaviour of waves of moderate amplitude is also simulated. [Copyright &y& Elsevier]

This paper describes the use of adaptive hierarchical grids to predict incompressible separated flow at low Reynolds number. The grids consist of a quadtree system of hierarchical Cartesian meshes which are generated by recursive subdivision about seeding points. The governing equations are discretized in collocated primitive variable form using finite volumes and solved using a pressure correction scheme. The mesh is locally adapted at each time step, with panel division or removal dependent on the vorticity magnitude. The resulting grids have fine local resolution and are economical in array size. Results are presented for unidirectional, impulsively started flow past a circular and a square cylinder at various Reynolds numbers up to 5000 and 250 respectively. It is clear that hierarchical meshes may offer gains in efficiency when applied to complex flow domains or strongly sheared flows. However, as expected, the stepped approximation to curved boundaries resulting from the Cartesian quadtree representation adversely affects the accuracy of the results for flow past a circular cylinder. © 1998 John Wiley & Sons, Ltd.

Concurrent articulatory suppression does not appear to attenuate the effect of phonemic similarity upon short-term recall under conditions of auditory presentation. On theoretical grounds, the effect should be entirely abolished with visual presentation, but the available evidence is equivocal. The present study investigated the immediate serial recall of visually presented sequences of letters and words. Articulatory suppression reduced the overall performance and eliminated the phonemic similarity effect.

This paper presents a two dimensional two-way coupled model combining Smoothed Particle Hydrodynamics (SPH) based on the Navier–Stokes equations (NSE) and OceanWave3D based on the fully nonlinear potential flow theory (FNPT) in order to efficiently simulate non-linear waves and wave–structure interaction problems. The two models are strongly coupled in space and time domains using a fixed overlapping zone, wherein the information from both solvers is exchanged by relaxation functions. In the SPH model, an open relaxation boundary, which is implemented as open and relaxation zones, is used in the coupling region. Horizontal velocity and free surface elevation in the open and relaxation zones are obtained from OceanWave3D, while vertical velocity and density in the open zones are interpolated from the relaxation region. OceanWave3D requires the free surface elevation and vertical velocity at the free surface from SPH in the coupled region. The coupled model is tested by modelling a regular wave, irregular wave and wave over a submerged bar and an oscillating water column (OWC) device. The results demonstrate that the coupled model can produce satisfactory results with less computational time than the SPH-only model. • A two-way coupling model between OceanWave3D and SPH is proposed. • Coupling region in SPH is implemented as open relaxation boundary. • The coupled model is computationally cheaper than an SPH-only model. [ABSTRACT FROM AUTHOR]

This paper presents a new Smoothed Particle Hydrodynamics (SPH) parallel framework, which is designed for free surface flows and is scalable on a High Performance Computer (HPC). The framework is accomplished by adopting a Message Passing Interface (MPI) approach with a domain partitioning strategy. A regular background grid is used to partition the entire computational domain and each subdomain is labelled using an index ordering method. Adjacent subdomains can be determined by the index list, and avoid global communications in the particle distribution process. Within the local grid, the grid is divided into an internal grid as well as an interactive grid to identify the particles for which information is to be transferred. The implementation of the dynamic loading balance strategy considers two different ways of determining loading: computation particle numbers and running time. The dynamic load balance strategy repositions neighbouring subdomains based on the local load imbalance between cores. To demonstrate the framework's capacity and distinctive properties, a variety of free surface flow benchmarks are studied. Intensive numerical experiments at various scales are used to assess the performance in detail. • We propose a new MPI-based parallel SPH framework for free-surface flow. • A dynamic load balance strategy is applied in the parallel SPH framework. • The SPH framework works well for free surface conditions with large deformation. • Time cost-based balancing strategy is more efficient than the particle number-based. [ABSTRACT FROM AUTHOR]