The horizontal and vertical motions at the surface of swelling poroelastic layer in coupled system are investigated. Coupled system means water-swelling porous sediment-elastic solid substrate system. The analytical expressions of horizontal and vertical displacements at the surface of swelling porous solid are evaluated for both incidences i.e., P and SV waves. The closed form analytical expressions

The existing stress field evaluation formulas for V-shaped and U-shaped notches are complicated and limited to certain specific opening angles. Based on linear elastic fracture mechanics and singular strength theory, the traditional calculation formula of notch stress distribution is simplified by introducing singular intensity factors, and the notch stress formula suitable for different opening angles

The dynamic response of the coiled tubing (CT)-in-riser system is critical to the success of offshore CT operations. The purpose of this work is to investigate the mechanical behavior of the CT and the riser and analyze the influencing factors of the coupled system. This paper builds dynamic models of the micro elements of the CT and the riser, and then a coupled model of the CT-in-riser system is

In high flow velocity areas, turbulence intensity is high and flow variations may have a major impact on tidal turbines behaviour. Previous studies show that a square wall-mounted cylinder produces a very extended and energetic wake. In this work, two-component PIV measurements are conducted in the symmetry plane of the flow in order to evaluate the Turbulent Kinetic Energy (TKE) budget. This analysis

The resistance and ship-generated waves of two inland vessels in the fully-confined waterway are investigated based on numerical simulations. The simulation results are validated using towing tank experiments. The influences of the channel dimension, water depth, ship draught and velocity are studied. Specially, the ship resistance is characterized as a function of the blockage ratio and the theory

A methodology for directly establishing the forces and moments on a maneuvering body based on the instantaneous state of the vehicle is demonstrated. Both classical and modern Design of Experiments were used to develop experimental design regions consisting of different combinations of inflow conditions. Data was generated using computational fluid dynamic simulations which were performed on DARPA

While maneuvering or positioning in different situations, the hull, the angle of the inlet current, and the tunnel opening fairing onto the hull have serious impacts on the performance of the bow thruster. The co-operation of multiple bow thrusters affects each other in the hydrodynamic performance. In this study, we report a thorough investigation of the hydrodynamic performance of the bow thruster

The net buoyancy, driving force of underwater gliders, decreases gradually when the gliders dive or climb in the seawater, which increases the energy consumption and reduces the gliding range. The neutrally buoyant hull is an effective measure to reduce this buoyancy loss of underwater gliders. In this paper, a multiple intersecting spheres (MIS) pressure hull is designed to provide neutral buoyancy

In this paper, cross-flow vibrations of two identical elastically mounted circular cylinders in tandem arrangement have been investigated in a wind channel at Reynolds number Re = 4000–42000. The spacing ratios S/D are from 1.2 to 8.0. The vibration amplitude, oscillation frequency fo and vortex shedding frequency fs are investigated. Based on the vibration characteristics, three regimes can be classified

This paper investigates the numerical prediction of cavitation and hull pressure pulses induced by a marine propeller operating in behind-hull conditions of a container vessel in model scale. Simulations are performed using commercial package Star-CCM+ and opensource package OpenFOAM using RANS approach and predictions are compared with experimental measurements. A mesh dependency study with respect

This paper presents a study on reconstruction errors of wave force around a circular cylinder using measured wave elevation data through theoretical analysis and experimental validation. Since the accuracy of reconstructed results is directly subjected to the collected data of wave elevation, some unexpected errors can be injected into the results as the data are not informative enough. A mathematical

The vortex-induced motion (VIM) of semi-submersible is gaining increasing attention from both industry and academia with the recent development of deep draft semi-submersible platforms. Field measurements of semi-submersibles reveal that the VIM responses are typically found to be smaller than those observed in model tests. The possible factors causing the VIM response reduction in the field measurements

In this study, a series of model tests was conducted to investigate the characteristics of wave impact loads and the associated air bubble effects on a vertical circular cylinder with various pressure and force sensors installed in a 2D wave flume. Spilling and plunging waves, generated by the focusing wave method, induced wave impact loads on the cylinder, and these loads were measured by the sensors

Model testing of offshore floating wind turbines (FOWTs) needs to account for the hydrodynamics of the floater at the same time as the aerodynamics of the rotor, and their interactions. Testers have followed two distinct paths to solve the challenge of modelling these two dissimilar physical phenomena. One path has consisted of building physical models at basin scale that resembled the actual FOWT:

In this paper, hydrodynamic characteristics of two-dimensional submerged breakwaters in water of finite depth and infinite domain interacting with sinusoidal waves are studied from both analytical and numerical approaches. Added mass and damping coefficients are obtained following the determination of radiation potentials in three degrees of freedom (sway, heave and roll). Diffraction problem is then

Flow-induced vibrations (FIV) of the cylinder with an upstream wake interference is rather different and more complex comparing with vortex-induced vibrations (VIV) of an isolated cylinder in the uniform flow, due to the wake interference mechanism involved. In this study, the forced vibration experiment is carried out on a rigid cylinder placed in tandem downstream of a stationary cylinder. The hydrodynamic

This study investigated variations in directional wave parameters by using various combinations of the GNSS buoy data, such as the displacements (enη) and the velocities (uvw) in the east, north, and upward directions. The investigated directional wave parameters included mean wave direction, directional spreading, directional wave spectrum, and dominant wave direction (DWD). The three combinations

Steel lazy wave risers (SLWRs) are regarded as an alternative option of advanced steel catenary risers (SCRs), and their nonlinear dynamic performance is a great challenge as subjected to vessel offsets and wave-current loads. Especially, the mechanical features would be more complicated due to the introduction of the buoyancy module system. This paper presents a numerical model based on three-dimensional

This paper presents an attempts towards creation of generalized models of ships manoeuvring area determination and ship performance created on the base of real simulation results. Those models are needed for better understanding of the safe navigation process in ports areas and its approaches and for risk analysis when no full information about the ships behaviour is available. The data coming from

Ship structures can experience damages although they are initially designed with high safety factors. These damages can be caused by many reasons such as collisions, groundings, explosions, corrosion, fatigue, overloading or extreme conditions. Brittle damages can occur on the ship structures in some special conditions such as low-temperature, high-loading rate, multi-axial stress constraint, or low

This paper addresses the tracking control problem of unmanned underwater vehicles under the condition of external disturbances and unmodeled dynamics using Port-Hamiltonian theory. By introducing Port-Hamiltonian theory, conventional UUVs dynamics can be transformed into Port-Hamiltonian form with insightful expressions. Then, combined with a structure preserving adaptive method, unmodeled dynamics

Numerical wave basins are a powerful tool for the study of fluid-structure interaction (FSI) problems in coastal and ocean engineering fields. Once well validated, numerical wave basins can offer significant advantages over experimental testing in terms of the number and type of available data-streams, and the associated cost. However, conventional numerical wave tanks tend to be limited to the generation

This study presents a novel fuzzy random reliability analysis method based on the cloud theory and investigates its applicability employing three numerical examples related to the structural reliability of breakwaters. The results which are compared with the calculations of the traditional (i.e., MCS, FORM), as well as non-traditional (i.e., FMCS, ANN based MCS), methods show that the presented method

The objective of this paper is to predict the dipole noises caused by the marine propeller of an oceanography research ship, and compare the calculated results with the experimental data to verify the applied numerical method. As the propellers are of free-cavitation, such as those of submarines at diving depth and the surface vessels operating at cruising speed, the dominant noises are generated by

Flow patterns downstream of the hollow square cylinder with slots are experimentally investigated to show effect of the slot ratio on the wake flow characteristics and turbulence statistics at Reynolds number of Re = 6000 using the particle image velocimetry (PIV) technique. Proper orthogonal decomposition (POD) analyses indicate that the self-issuing jet dramatically changes the mechanism of vortex

Numerous constructed jacket platforms in the Persian Gulf require continuous monitoring due to aging which poses a significant hazard to the environment. The main aim of this study is to sketch a health monitoring system to address the problem of limitations and shortcomings of sensor networks and also to solve the localization problem. In order to achieve this goal, experimental modal analysis (EMA)

This paper proposes a semi-empirical model to estimate a ship’s speed loss at head sea. In the model, the formulas to estimate a ship’s added resistance due to waves have been further developed to better consider the ship hull forms, in addition to other main particulars. Based on the model experimental tests of 11 ships in regular head waves, the new formulas have more flexible forms and can better

The importance of reducing the noise impact of ships is being recognised worldwide. Consequently, the inclusion of this principle among the objectives and constraints of new designs is becoming a standard. For this reason, considerable attention is given to the propeller being often the dominant source of underwater radiated noise, especially when cavitation occurs, as it happens in most cases when

A meshless CFD method is proposed for numerical simulation of incompressible flows and estimation of hydrodynamic loads during green water events. In this paper, governing equations are described in Finite Differences context, where spatial operators are derived using Weighted-Least Squares. Volume-conservative Lagrangian advection is handled by solving a set of geometrical constraints, while adjusting

The localization performance of single beacon navigation system is affected by the accuracy of effective sound velocity (ESV) which is difficult to precisely know. The state augmented method and expectation–maximization (EM) based method, the two existing state-of-the-art single beacon navigation methods which can deal with the unknown ESV, are sensitive to the noise statistic parameters and vehicle

The twin vertical-axis wind turbine (VAWT) system is a high-performance design in which two turbines are placed side by side with a variable gap distance. In this paper, the large eddy simulation and the sliding mesh technique are employed to numerically study the aerodynamic performance of the dual-rotor configuration. First, the reliability of this CFD model is validated, including computational

Advances in artificial intelligence are driving the development of intelligent transportation systems, with the purpose of enhancing the safety and efficiency of such systems. One of the most important aspects of maritime safety is effective collision avoidance. In this study, a novel dual linear autoencoder approach is suggested to predict the future trajectory of a selected vessel. Such predictions

The operational requirements for naval and research vessels have seen an increasing demand for quieter ships either to comply with the ship operational requirements or to minimize the influence of shipping noise on marine life. The radiated noise of a ship is estimated during the design stage by measurements with a scale model, generally realized in a tunnel or a depressurized tank. DGA Hydrodynamics

The main purpose of this work is to shed light on the physics involved in the two distinct cavity cloud shedding mechanisms in cloud cavitating flows, namely re-entrant jet mechanism (RJM) and shock wave propagation mechanism (SWM). A compressible cavitating flow solver, which considers the compressibility effects of both liquid and vapor, is used to account for the wave dynamics in cavitating flows

The present study analyzed 41 years of ERA-5 wind-wave data (1979–2019) to understand the long-term trend, inter-annual, and inter-seasonal variability of total wind-generated waves, wind-seas, and swell waves in the Indian Ocean (IO). The significant wave height (SWH) of ERA-5 was validated with the multi-platform calibrated altimetry wave height. The correlation coefficient of SWH was about 0.97

Deep-draft semi-submersible platforms may present significant second-order resonant motions in severe sea states. Evaluating the slow-drift motions of such floating systems is important from the initial stages of their designs considering not only the offset requirement and mooring line load but also the air-gap responses beneath the lower deck. Theories and corresponding applications for these second-order

To design eco-friendly ships, the hydrodynamic behaviour of the hull has to be estimated precisely. The first and foremost one is the ship resistance, which is closely related to the energy efficiency of the ship. Different extrapolation methods, based on different assumptions, have been used to predict the full-scale ship resistance from model-scale experiments. In this manner, it is important to

Box-type floating breakwaters have been studied extensively. However, the examinations of the performances of them with different shapes or different numbers of boxes are limited. In addition, if it is possible to optimize the floating breakwaters by combining the optimized parameters in separated testing groups is still unclear. Consequently, in this study, four typical box-type floating breakwaters

Compared to metals, composite materials have many advantages such as lightweight, high strength-to-weight ratio, and reduced noise properties. The anisotropic nature of carbon fiber reinforced plastic (CFRP) with different stacking sequences and fiber angles can be used to build a composite propeller with enhanced hydrodynamic and mechanical properties. The primary objective of this paper is to analyze

This study develops analytical solutions for Bragg scattering of water waves propagating over a series of submerged perforated semi-circular breakwaters (bars) based on potential theory. The series solutions for velocity potentials in the external common fluid domain of the bars are expressed through multipole expansions, whilst those in the internal fluid domains are given using the separation of

The hydrodynamic characteristics of a waterjet-propelled amphibious craft traveling in displacement and planing modes are studied via full-scale experiments and numerical simulations in three ways. First, variations of pitch, resistance, and vertical rise for speeds from 2 to 18 knots are investigated. As speed is incrementally increased, pitch and resistance increase geometrically before maximizing

The interaction between cnoidal waves and a concentric cylindrical structure with an arc-shaped outer wall has been investigated theoretically using eigenfunction expansion approach. The arc-shaped outer cylinder is permeable and thin, protecting the porous dual-cylinder structure. Three cylinders are surface-piercing and rigidly installed on the flat bottom of an ocean. Analytical solutions were obtained

This paper considered the problem of numerical simulation of an incompressible dam break flow consisting of three phases. The movement of the water free surface is performed using the Newtonian fluid model, and the mud mixture movement is carried out by the non-Newtonian fluid model based on the VOF method. The PISO numerical algorithm was selected as a numerical method for solving equations. This

One of the main causes of the formation of internal waves is the ocean currents, from the seabed's mounds. For this reason, numerous empirical studies have been carried out in laboratories on the flow of streams on artificial mounds or the passage of objects in a stratified medium. The purpose of this study is to identify the changes in the density of the layers by internal waves due to the movement

This paper presents a resource-aware state and uncertainty estimation method for dynamic positioning vessels subject to uncertain kinetics and unknown sea loads induced by wind, waves and currents. Specifically, an event-triggered extended state observer (ESO) is proposed such that unnecessary communications are avoided and sensor-to-observer communication cost are drastically reduced. A realizable

Marine propeller ventilation, which can occur in extreme seas, reduces energy efficiency of the ship, and can result in significant safety hazards during navigation. A major maritime challenge is to predict water levels during extreme seas and manage an appropriate control strategy for the propulsion system with fast response times. Here we report application of an evidence reasoning (ER) rule-based

Floating offshore wind turbines are becoming more attractive to the wind industry due to their capability to operate larger turbines in deeper waters. The floating support structures are anchored to the seabed via mooring chains to impede the structure's unwanted movements. The combination of cyclic stresses and the corrosive marine environment makes the floating support structures vulnerable to corrosion

The bond between epoxy-coated reinforcement (ECR) and seawater coral aggregate concrete (SCAC) were studied by using a series of pull-out tests. Five different parameters were considered in this test: types of concrete (SCAC and ordinary concrete (OC)) and reinforcement (ECR and ordinary reinforcement), the ratio of bond length to reinforcement diameter (3, 5 and 8), and concrete strength (C25 and

Waters surrounding Zhoushan Archipelago have the most abundant tidal current energy in China, which makes it a promising site for tidal farm construction in the future. Before deploying tidal current turbines, the potential environmental impacts on surrounding waters must be evaluated. In this work, we focus on the flow field impact assessment of an assumed tidal farm installed in Zhoushan Putuo-Hulu

This study provides empirical formulae of wave loads on quasi-ellipsoid-type foundations coaxially surrounded by perforated breakwaters. The variation of the wave load on each structure versus wave number is characterized as a polygonal line by four key points. The coordinates of these points can be directly obtained from the empirical formulae, which are developed by using mathematical models in the

As a deep-water foundation, composite caisson-pile foundation (CCPF) is usually subjected to horizontal dynamic loads and moments due to the complicated marine environment. In this study, model tests were performed on three different types of deep-water foundation, including caisson, caisson with four piles and eight piles to investigate their lateral nonlinear dynamic characteristics under various

The low-frequency (1/400- 1/30 Hz) oscillations within the Hambantota Port, Sri Lanka, are investigated based on the in-situ measured water surface elevations in and outside the harbor. By combining analyses of spectra derived from the in-situ measurement and modal analyses solving the extended mild-slope equation, four natural frequencies of the port are identified and their modal structures are obtained

Maritime transportation poses various risks that may lead to the loss of life and property damage. This paper presents a spatial fuzzy multi-criteria evaluation approach for assessing and mapping maritime transportation risk by combining geospatial techniques and multi-criteria decision making. Fourteen criteria in three risk component categories (hazard, vulnerability and exposure, and mitigation

The increasing relevance of simulation-based design has created a need to accurately estimate and bind numerical errors. This is particularly relevant to full-scale computational ship hydrodynamics, where measurements are difficult and expensive, simultaneously requiring a high degree of predictive accuracy even in early design stages. However, the field of ship hydrodynamics has yet to fully exploit

A hybrid tsunami defense system comprising vegetation (V), an embankment (E), and a moat (M) while changing the order of the components and the inundation depth of vegetation was investigated in a flume using a surge-type flow produced by quickly lifting a gate. Compared with the hybrid defense system in which vegetation is emergent, the tsunami mitigation effects of seaward vegetation became smaller

Statistical analysis of past maritime accidents may demonstrate the trends for certain contributing factors. However, there is a lack of a technique, which is capable of handling complex nature of maritime accidents by modelling interrelations between contributing factors. Due to the aforementioned complex interrelations and insufficient detail stored in accident databases about these contributors

This paper proposes a local mesh reconstruction method designed for generating the finite element (FE) analysis model in the context of simultaneous layout and scantling optimization. The FE model is automatically built by inheriting the topology and property information of the prepared initial finite element (FE) analysis model. A framework of optimization integrating the mesh reconstruction process

Scour that removes soils around foundations supporting bridges and marine structures is the major cause for structural failures. Recently, many studies have been conducted to investigate scour effects on lateral behavior of single piles using numerical analyses, laboratory model tests, or centrifuge tests. However, very limited research is focused on scour effects on lateral behavior of pile groups

Based on wave measurements lasting four and a half years, wave characteristics in a lagoon of the South China Sea are discussed in this paper. The significant wave height (Hs), mean periods (Tz) and wind speed (Ws) are mostly smaller than 1 m, 6 s and 15 m/s, respectively. Based on the monthly average Hs, there exists a transition season between winter and summer in the first half of the year. Waves