Numerical investigation of the stability of armour units in low-crested breakwaters using combined SPH–Polyhedral DEM method

Sarfaraz, Mohammad; Pak, Ali

doi:10.1016/j.jfluidstructs.2018.04.016

Cited by 18 publications

(2 citation statements)

References 49 publications

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“…In order to protect engineering structures and the coastline from ocean waves, researchers have been paying attention to exploring various methods to reveal the interaction between breakwaters and waves. Variable types of breakwaters have been developed and analyzed in recent decades, such as various kinds of bottom-mounted breakwaters and floating breakwaters [1], [2], [3], [4], [5], [6], [7], [8], [9]. Among them,…”

Section: Introductionmentioning

confidence: 99%

A Model Coupling CFD and DRL: Investigation on Wave Dissipation by Actively Controlled Flat Plate

et al. 2022

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In order to protect structures along the offshore and off the coast, breakwaters are commonly applied to reduce the influence of waves. Flat plate breakwater is studied frequently due to its great performance near the water surface, however, traditional passive methods such as fixed and floating flat plate breakwaters usually fail to give full play of effective wave dissipation when encountering variable unknown incoming waves. Therefore, this paper develops an interdisciplinary model coupling computational fluid dynamics (CFD) and deep reinforcement learning (DRL) to study the wave dissipation of a submerged movable flat plate breakwater against regular waves. An in-house numerical wave tank (NWT) is built to simulate the fluid-structure interaction between the plate and regular waves. The fluid domain in NWT is regarded as environment while the flat plate breakwater is agent. In addition, the wave dissipation strategy is learned by the artificial neural network (ANN) through the continuous wave-plate interaction. It is excited to find that the coupling model is able to learn the control strategies automatically and exhibits good adaptability to the changes of environment. 13 14 INDEX TERMS Wave dissipation, deep reinforcement learning, flat plate breakwater, active controlling, CFD and DRL. culated, of which the results showed that a suitable geo-49 metrical porosity of the upper plate leads to a low level of 50 uplift wave forces on both plates. Reference [17] investi-51 gated the flow field passing over a submerged horizontal 52 flat plate by means of a free surface potential flow model, 53 a form discretized by the Boundary Element Method (BEM), 54 from which the wave dissipation mechanism of a plate-55 type breakwater and the influence of plate thickness, length 56 and submergence was concluded. Reference [18] presented 57 an integrated CFD+CSM approach to fully simulate the 58 hydroelastic interaction between nonlinear ocean waves and 59 a deformable SHPB device, making two major contributions: 60 (a) the research work demonstrated a valid computer-aided 61 approach that can perform hydroelastic offshore and coastal 62 designs; (b) the researching work demonstrated a hydroelastic 63 design methodology for breakwaters for the first time and 64 showed that the deformation of the structure has a significant 65 effect on the wave-damping performance. References [19] 66 and [20] conducted an experiment to research the wave dissi-67 pation performance of a twin-plate considering various wave 68 conditions. References [21] and [22] investigated the interac-69 tion between freak waves based on numerically investigating 70 the interaction characteristics of horizontal deck structures 71 and freak waves, which revealed the corresponding phenom-72 ena, wave loads, and structural response. Reference [23] 73 further studied the interaction between Peregrine breather-74 based freak waves and twin-plate breakwaters, including the 75 characteristics of interaction phenomena, transmitted wave 76 surface, wave loads, and st...

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Section: Introductionmentioning

confidence: 99%

A Model Coupling CFD and DRL: Investigation on Wave Dissipation by Actively Controlled Flat Plate

et al. 2022

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“…DualSPHysics [58] was also applied by Zhang et al [66] to compute the wave run-ups on a breakwater seated in Chongwu town, China, using the realistic wave conditions, bathymetry and dimensions. By combining the SPH method and the discrete element method, Ren et al [67] and Sarfaraz and Pak [68] investigated the wave profiles, velocity fields and hydraulic pressure near the armor blocks laid on the slope breakwaters. Moreover, the stability of the armor layers during wave attacks was inspected.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Hydrodynamic Characteristics of a Double-Row Floating Breakwater Composed of a Pontoon and an Airbag

Cheng

Liu

Zhang

et al. 2021

JMSE

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By adding a cylindrical airbag on the leeward side of a cuboid pontoon, a new-type double-row floating breakwater is designed to improve the wave attenuation performance, and its hydrodynamic characteristics are studied through numerical simulations. First, based on the smoothed particle hydrodynamics (SPH) method, a numerical model used to simulate the interaction between waves and moored floating bodies is built. The fluid motion is governed by the Navier–Stokes equations. The motion of the floating body is computed according to Newton’s second law. The modified dynamic boundary condition is employed to treat the solid boundary. The lumped-mass method is adopted to implement the mooring system. Then, two physical model experiments on waves interaction with cuboid and dual cylindrical floating pontoons are reproduced. By comparing the experimental and numerical wave transmission coefficients, wave reflection coefficients, response amplitude operators and mooring force, the reliability of the numerical model is validated. Finally, the validated numerical model is applied to study the influence of separation distance and wave parameters on the hydrodynamic characteristics of the double-row floating breakwater. The results indicate that the optimal separation distance between pontoon and airbag is 0.75 times the wavelength. At such separation distance and within the concerned 1–4 m wave heights and 4–7 s wave periods, the pontoon-airbag system presents better wave attenuation performance than a single pontoon. This improvement weakens as wave height increases while it strengthens as the wave period increases. In addition, the double-row floating breakwater is more effective in a high-wave regime than in a low-wave regime. In the case of short waves, attention should be paid to the stability and mooring reliability of the seaward pontoon, while in the case of long waves, care needs to be taken of the leeward airbag.

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Weakly compressible SPH simulation of cnoidal waves with strong plunging breakers

Sarfaraz

Pak

2019

Ocean Dynamics

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Numerical investigation of the stability of armour units in low-crested breakwaters using combined SPH–Polyhedral DEM method

Cited by 18 publications

References 49 publications

A Model Coupling CFD and DRL: Investigation on Wave Dissipation by Actively Controlled Flat Plate

A Model Coupling CFD and DRL: Investigation on Wave Dissipation by Actively Controlled Flat Plate

Numerical Study on the Hydrodynamic Characteristics of a Double-Row Floating Breakwater Composed of a Pontoon and an Airbag

Weakly compressible SPH simulation of cnoidal waves with strong plunging breakers

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