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S. John Ashlin

Bio: S. John Ashlin is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Oscillating Water Column & Froude number. The author has an hindex of 4, co-authored 6 publications receiving 118 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the influence of bottom profile configuration in the oscillating water column (OWC) on its hydrodynamic performance was studied in terms of wave amplification factor, wave power absorption coefficient, hydrodynamics efficiency, lip wall pressure ratio, and air pressure ratio.

77 citations

Journal ArticleDOI
TL;DR: In this article, the effect of different spacing between an array of oscillating water column (OWC) devices integrated with offshore detached breakwater (ODBW) in terms of their hydrodynamic performance has been studied.

45 citations

Journal ArticleDOI
TL;DR: In this paper, a series of experiments were conducted in a wave flume, 72.5m long, 2m wide and 2.5 m deep, where a custom made strain gauge based force transducer has been mounted to measure two force components namely vertical and horizontal.

32 citations

Book ChapterDOI
01 Jan 2019
TL;DR: In this article, a systematic numerical investigation on the hydrodynamic performance of an oscillating water column (OWC) system for different damping values from the power take off (PTO) device and at different model scales has been studied.
Abstract: A systematic numerical investigation on the hydrodynamic performance of an oscillating water column (OWC) system for different damping values from the power take-off (PTO) device and at different model scales has been studied. Further, an experimental programme was devised with a Froude model scale of 1:12 in a shallow wave flume by representing PTO damping by varying the air orifice ratio, a/A [ratio of air orifice area (a) to plan area (A)]. In the case of numerical investigation, simulation was carried out in the computational fluid dynamics (CFD) model, REEF3D. Herein, the equivalent PTO damping on the OWC chamber is represented by the porous media flow relation. First, the numerical results are validated by comparing with the laboratory measurements for five different PTO damping. Second, following the validation stage, the open-source numerical model is used to evaluate model scale effects on the hydrodynamic performance of the OWC by comparing hydrodynamic parameters of four different model scales from 1:12 to full scale. In this paper, the influence of PTO damping and model scales on the variation of pressure behind the lip wall, air pressure, and hydrodynamic efficiency is studied. The results are reported for different relative water depths. Since the air is modelled as incompressible, the effect of scaling on the hydrodynamic performance of OWC is found with negligible variation.

3 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, wave reflection and loading on a generalised Oscillating Water Column (OWC) wave energy converter are investigated by means of large scale (approximately 1:5-1:9) experiments in the Grosse Wellenkanal (GWK), in which variation of both still water depth and orifice (PTO) dimension are investigated under random waves.

91 citations

Journal ArticleDOI
13 Nov 2019-Energies
TL;DR: In this article, the authors compared the efficiencies and power performance of different wave energy converters and found that the oscillating body systems have the highest ratio in terms of the efficiency per characteristic width, and overtopping devices have the lowest.
Abstract: The level of awareness about ocean wave energy as a viable source of useful energy has been increasing recently. Different concepts and methods have been suggested by many researchers to harvest ocean wave energy. This paper reviews and compares the efficiencies and power performance of different wave energy converters. The types of analyses used in deriving the reported efficiencies are identified, and the stage of the power conversion processes at which the efficiencies were determined is also identified. In order to find a common way to compare the efficiencies of different technologies, the hydrodynamic efficiency in relation to the characteristic width of the wave energy converters and the wave resource potential are chosen in this paper. The results show that the oscillating body systems have the highest ratio in terms of the efficiency per characteristic width, and overtopping devices have the lowest. In addition, with better understanding of the devices’ dynamics, the efficiencies of the newer oscillating water column and body systems would increase as the potential wave energy level increases, which shows that those newer designs could be suitable for more potential locations with large variations in wave energy potentials. At last, discussion about the cost of ocean wave energy is presented as well.

86 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of an oscillating water column wave energy converter is investigated based on both numerical and experimental approaches, where the viscosity effects are neglected in the numerical approach and the boundary integral equation method (BIEM) is implemented to solve the appropriate 2D boundary value problem (BVP).

80 citations

Journal ArticleDOI
01 Dec 2016-Energy
TL;DR: In this article, a fully nonlinear 2D RANS-based computational fluid dynamics (CFD) model was used to carry out an energy balance analysis of an onshore OWC.

70 citations

Journal ArticleDOI
TL;DR: In this article, the hydrodynamic response of two types of Bent Duct OWC devices with different inlet geometries, both in isolation and when implemented in a flat-faced breakwater, was investigated.

60 citations