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.
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.
TL;DR: In this article, a physical model study is carried out to assess the wave forces acting on a single and twin wave barriers of various porosities under a wide range of wave conditions.
Abstract: Vertical slotted barriers are cost effective energy-dissipating structures The design of such barriers requires an accurate estimation of dynamic pressures and resulting wave forces Herein, a physical model study is carried out to assess the wave forces acting on a single and twin wave barriers of various porosities under a wide range of wave conditions The study provides explicit data on how dynamic pressures vary vertically from the seabed to the still water surface and on the resulting forces, both seaward and shoreward In particular, the experimental results indicate that porosity affects dynamic pressures significantly especially near the free surface, but less so closer to the seabed Further, resultant horizontal wave forces seaward are 20–25% less than shoreward forces Forces on the front panel in the twin wave barrier cases are 20–25% more than those on a single porous wall while the forces on the rear or second barrier is always 20–25% less than the single wave-barrier case under identical test conditions These and other results presented in the study can be useful in designing wave dissipaters, especially for inner harbors and vertical sea walls
TL;DR: In this paper, a sea water intake well of size 20m diameter and 15.5m height in a water depth of 9.8m is proposed for a project to extract magnesia from sea water.
Abstract: A sea water intake well of size 20 m diameter and 15.5 m height in a water depth of 9.8 m is proposed north of the Visakhapatnam Port for a project to extract magnesia from sea water. A 1:25 scale model of the intake well was tested in the wave basin of the Ocean Engineering Centre, Indian Institute of Technology, Madras to measure the wave forces and moments on the intake well and the variation of water levels inside and outside the well. Accordingly, an intake well model of 0.8 m diameter and 0.62 m height was fabricated and fixed over a false bottom in a wave basin. The well model was subjected to the action of both regular waves for two test conditions, intake well inlet closed during installation and intake well inlet open. The experimental results on wave forces and moments were compared with the results of the Linear Diffraction Theory. The water level inside the well was measured to determine the submergence of suction pipes of pumps and location of the inlet opening of the intake well. The wave crest elevation in front of the well was also measured in order to fix the deck level of the well so as to avoid water overspill onto the deck. The salient results of the present study are presented and discussed in this paper.
TL;DR: In this article, a multi-domain boundary element method (MBEM) is applied to study wave interaction with double vertical slotted walls, which are modeled as thin or non-thickness structures.
Abstract: In this paper, a multi-domain boundary element method (MBEM) is formulated and applied to study wave interaction with double vertical slotted walls, which are modeled as thin or non-thickness structures. Two-dimensional motion with wave crests parallel to the vertical slotted walls and linearized irrotational flow are assumed. The accuracy of the solution obtained using the numerical technique is demonstrated by comparing the numerical values with those obtained from experiments and from other analytical solutions. A comparison of the hydrodynamic performance of the breakwater with identical or different double vertical slotted walls is conducted. In addition, the numerical results of the wave reflection, transmission and energy dissipation for different relative permeable depths, chamber widths, and porosities are presented and discussed. Double vertical slotted walls with a longer rear wall are recommended because they more effectively suppressed wave energy at deeper submergence. The double vertical slotted walls also very effectively dissipate the incident wave energy. Our numerical results indicate that when the permeable middle part of the seaward (first) wall (dm_1/h = 0.6) and the permeable middle part of the leeward (second) wall (dm_2/h = 0.2) have different porosities of e_1 = 0.5 and e_2 = 0.3, respectively, the breakwater has a high reflection coefficient, a low transmission coefficient and the maximum energy dissipation coefficient. The maximum energy dissipation coefficient of 0.963 occurs at kh = 1.635.
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