Effect of Porous Curtain Wall on the Internal Hydrodynamics of an Offshore Intake Well
01 Jan 2021-pp 481-492
TL;DR: In this paper, the internal hydrodynamics of an offshore intake well with a porous curtain wall were investigated with regular waves in the shallow wave basin and wave run-up, rundown, free surface water oscillation inside the well and the pressure acting on the curtain wall was measured.
Abstract: The purpose of offshore seawater intake is to provide a continuous supply of seawater with proper quantity and quality. The large volume and specified water quality requirements, offshore intake wells are preferred. The adequate and economical supply of seawater from the offshore intake well depends on the performance of the pumping system. In a typical intake well, the pumping equipment is placed below the water surface based on the free surface water oscillation inside the well. The loads exerted by the incoming waves and the free surface water oscillation will affect the pumping performance. This phenomenon should be reduced for smooth and efficient pumping operation. To achieve this, some auxiliary equipment like curtain wall is introduced into the intake well. This type of internal structure can regulate the flow and dissipate the incident wave energy up to some extent. Moreover, they can obstruct the formation of vortices and eddying. The present study focuses on the internal hydrodynamics of an offshore intake well with a porous curtain wall. A 1:20 scale model is tested with regular waves in the shallow wave basin and wave run-up, rundown, free surface water oscillation inside the well and the pressure acting on the curtain wall is measured. Then, the influence of the porosity on the free surface water oscillation is investigated by changing the porosity.
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21 Feb 2022
TL;DR: In this article , the wave-structure interaction of an offshore intake well with a curtain wall is computationally investigated with regular waves using ANSYS-FLUENT, Computational Fluid Dynamics (CFD) tool.
Abstract: The wave-structure interaction of an offshore intake well with a curtain wall is computationally investigated with regular waves. The simulation is done using ANSYS-FLUENT, Computational Fluid Dynamics (CFD) tool. The computational domain is governed by continuity and the Reynolds Averaged Navier-Stokes (RANS) equations and modeled in a Cartesian grid system. The combination of structured and unstructured mesh is used to discretize the simulation domain. The numerical model is developed based on the pressure-based transient solver, and the Volume of Fluid (VOF) technique is selected to trace the free surface elevation. The simulations are performed using the 1:20 scale model by varying wave period (T) and wave steepness (H/L). The run-up on the seaward face and pressure on both sides of the curtain wall are measured. The numerical run-up shows good agreement with the experiments for the d/L range of 0.15 to 0.36. The pressure on both sides decreases with increased d/L values and follows the same trend as experiments.
References
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TL;DR: In this article, the authors presented a numerical model of wave interactions with a thin vertical slotted barrier extending from the water surface to some distance above the seabed, and described laboratory tests undertaken to assess the numerical model.
Abstract: The present paper outlines the numerical calculation of wave interactions with a thin vertical slotted barrier extending from the water surface to some distance above the seabed, and describes laboratory tests undertaken to assess the numerical model. The numerical model is based on an eigenfunction expansion method and utilizes a boundary condition at the barrier surface that accounts for energy dissipation within the barrier. Numerical results compare well with previous predictions for the limiting cases of an impermeable barrier and a permeable barrier extending down to the seabed. Comparisons with experimental measurements of the transmission, reflection, and energy dissipation coefficients for a partially submerged slotted barrier show good agreement provided certain empirical coefficients of the model are suitably chosen, and indicate that the numerical method is able to account adequately for the energy dissipation by the barrier. The effects of porosity, relative wave length, wave steepness, and irregular waves are discussed and the choice of suitable parameters needed to model the permeability of the breakwater is described.
147 citations
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TL;DR: In this article, the authors presented the numerical calculation of wave interactions with a pair of thin vertical slotted barriers extending from the water surface to some distance above the seabed, and described laboratory tests undertaken to assess the numerical model.
Abstract: The present article outlines the numerical calculation of wave interactions with a pair of thin vertical slotted barriers extending from the water surface to some distance above the seabed, and describes laboratory tests undertaken to assess the numerical model. The numerical model is based on an eigenfunction expansion method and utilizes a boundary condition at the surface of each barrier which accounts for energy dissipation within the barrier. Comparisons with experimental measurements of the transmission, reflection, and energy dissipation coefficients for partially submerged slotted barriers show excellent agreement and indicate that the numerical method is able to adequately account for the energy dissipation by the barriers.
88 citations
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TL;DR: In this paper, the authors studied the wave runup and rundown at the leading and trailing edges of a perforated cylinder in a wave flume and found that the maximum wave run-up on the perforation is almost the same as the incident wave height.
Abstract: The regular wave interaction with a twin concentric porous circular cylinder system consisting of an inner impermeable cylinder and an outer perforated cylinder was studied through physical model and numerical model studies. The experiments were carried out on the twin concentric cylinder model in a wave flume to study the wave runup and rundown at the leading and trailing edges of the perforated cylinder. It was found that the maximum wave runup on the perforated cylinder is almost same as the incident wave height. The experimental results were used to develop the predictive formulae for the wave runup and rundown on the perforated cylinder, which can be easily used for design applications. The wave runup profiles around the perforated cylinder for different values of ka and porosities were studied numerically using Green's Identity Method. The results of the numerical study are presented and compared with the experimental measurements.
26 citations
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TL;DR: In this paper, the wave force on a seawater intake structure consisting of a perforated square caisson of 400 mm×400 mm size encircling a vertical suction pipe of 160 mm diameter is investigated using physical model studies.
Abstract: The wave force on a seawater intake structure consisting of a perforated square caisson of 400 mm×400 mm size encircling a vertical suction pipe of 160-mm diameter is investigated using physical model studies. The porosity of caisson was varied from 1.6 to 16.9%. Regular and random waves of wide range of heights and periods were used. It is found that the force ratio (ratio of the force on perforated caisson to the force on caisson with zero percent porosity) reduces to an extent of up to 60% with increase in porosity of the caisson from 1.6 to 16.9%. The force ratio was found to increase with increase in relative wave height and reduces with increase in relative width. Multiple regression analysis of the measured data points was carried out and predictive equations for wave force ratios are obtained both for regular and random waves. The results of this investigation can be used in the hydrodynamic design of perforated caissons, which are widely used as seawater intake structures.
21 citations
Journal Article•
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TL;DR: Wave forces on a vertical cylinder defensed by a perforated vertical and inclined barriers with 45° angle of inclination were experimentally investigated and the force ratios were found reducing with increase of wave steepness.
Abstract: Wave forces on a vertical cylinder defensed by a perforated vertical and inclined barriers with 45° angle of inclination were experimentally investigated. The relative wave height, (H i /d) varied from 0.114 to 0.429 and the porosity was kept constant with 12%. The force ratios were found reducing with increase of H i /d. It is estimated that on an average, the reduction of force on the vertical cylinder is about 35% due to perforated vertical barrier and is about 30% due to sloped barrier. Incident wave steepness, (H i /L) varied from 0.007 to 0. 080 and the force ratios were also found reducing with increase of wave steepness. The force ratios are less sensitive for the scattering parameter (ka).
13 citations
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