Masoud Hayatdavoodi

University of Dundee · School of Science and Engineering

This study is concerned with rigid-body responses and elastic motion of floating offshore wind turbines (FOWTs) under combined wave, current and wind loads. A numerical approach is developed in frequency domain based on the linear diffraction theory with a Green function for small current speeds and the blade-element momentum method for hydrodynami...

Waves generated by a horizontally moving disturbance on the seabed have been studied by developing two numerical models, namely, the Navier–Stokes and the Green–Naghdi equations. Various geometries of the bottom disturbances are considered, and waves generated due to a single motion and multiple oscillatory motions of the bottom disturbances are in...

Exercise-induced laryngeal obstruction (EILO) is a known cause of exertional dyspnoea, characterised by paradoxical inward collapse of laryngeal tissues. The pathophysiological mechanisms of EILO remain to be fully established, but insufficient mechanical resistance of laryngeal tissues to air-induced loads is hypothesised. It is understood that ai...

Interaction of nonlinear shallow water waves with a deformable seafloor represented by an infinitely long elastic sheet lying on a viscoelastic foundation is investigated. The study is motivated by damping features of muddy coastal areas on ocean waves. The mathematical model utilizes the Level I Green–Naghdi equations for the fluid flow and the th...

The underlying pathophysiological mechanisms of exercise-induced laryngeal obstruction (EILO) remain to be fully established. It is hypothesised that high inspiratory flow rates can exert a force on laryngeal airway wall that contributeto its inward collapse causing obstruction. Computational fluid dynamics (CFD) presents an opportunity to explore...

The strongly nonlinear Miyata-Choi-Camassa model, a two-layer internal-wave model that includes the free-surface effect (MCC-FS model), has shown excellent performance on simulating large-amplitude internal waves. In this study, we are interested in assessing whether the MCC-FS model can be applied to study problems involving surface waves, and how...

In this paper, a high-level Green–Naghdi (HLGN) model for large-amplitude internal waves in a two-layer fluid system, where the upper-fluid layer is of finite depth and the lower-fluid layer is of infinite depth, is developed under the rigid-lid free-surface approximation. The equations of the present HLGN model follow Euler's equations under the s...

Motion of a multi-unit wind-tracing floating offshore wind turbine (FOWT) to combined wave–current and wind is obtained in the frequency-domain. The linear diffraction wave theory with a Green function for small current speeds and the blade-element momentum method are used for the hydrodynamic and aerodynamic analysis, respectively. A finite-elemen...

We consider a horizontal, submerged plate in shallow water that is allowed to oscillate in the vertical direction due to the wave loads. The plate is attached to a linear spring and damper to control the oscillations. The focus of the study is on the transformation of the wave field by the submerged oscillating plate. To estimate energy scattering,...

An analytical approach and numerical solution to determine coupled aeroelastic and hydroelastic response of floating offshore wind turbines of arbitrary shape to combined wind and wave loads is presented. The model considers simultaneously the aerodynamic and hydrodynamic loads on an FOWT and integrates these with finite element method for structur...

This study is concerned with the interaction between nonlinear water waves and uniform current with moored, floating elastic sheets, resembling floating solar panels, floating airports, tunnels and bridges, and floating energy systems. The Green-Naghdi theory is applied for the nonlinear wave-current motion, the thin plate theory is used to determi...

Exercise-induced laryngeal obstruction (EILO) describes paradoxical laryngeal closure during inspiration at high-intensity exercise. It is hypothesised that during intense activity, the air-induced loads on supraglottic walls overcome their internal stiffness, leading to the obstruction. Recent investigations have revealed that the air-induced load...

Power production from a submerged wave energy device in shallow water is investigated in this paper. The energy device consists of a fully submerged, horizontal plate, which is restricted to vertical motions only. The plate undergoes vertical oscillations due to the wave-induced loads. Oscillations of the submerged plate are converted into electric...

Submerged oscillating plates are used as heaving plates to reduce the motion of floating objects, in wave energy devices to extract the wave energy, and as breakwaters to attenuate the wave field in shallow water. In this study, we consider a horizontal, submerged plate in shallow water that is allowed to oscillate in the vertical direction due to...

Floating pontoons of different shapes are used commonly as the base of floating offshore wind turbines, and as wave breakers to mitigate severity of incoming waves. The pontoons are typically attached to catenary mooring lines and often operate in areas subject to large environmental loads, including waves, current and wind. It is of interest to an...

Interaction of uniform and shear currents with nonlinear waves is studied by use of the computational fluid dynamics approach. A range of nonlinear waves are considered including shallow- and deep-water waves, and the effect of currents of variable speed and direction on the wave height is investigated. Uniform current consists of a fixed horizonta...

Missing person behaviour datasets indicate that a significant proportion of those reported missing are subsequently found deceased in water. Despite this, information about how human bodies move in an aquatic environment is limited. Created by a serving police officer and police search advisor, this study involved the collection and analysis of qua...

The approach used for wave–current generation and absorption is crucial for simulating waves propagating on currents in a numerical tank. An effective method for wave–current generation and absorption is proposed and validated in this study. In this approach, the numerical tank is divided into five regions: two linear, one nonlinear, and two transi...

Head-on collision of two solitary waves in the presence of linear shear currents is studied by the use of the High-Level Green–Naghdi (HLGN) theory. The finite difference method is used to solve the HLGN model in the time-domain simulation. The initial values are obtained by the steady solution of solitary waves in the presence of linear shear curr...

The strongly nonlinear Miyata–Choi–Camassa model under the rigid lid approximation (MCC-RL model) can describe accurately the dynamics of large-amplitude internal waves in a two-layer fluid system for shallow configurations. In this paper, we apply the MCC-RL model to study the internal waves generated by a moving body on the bottom. For the case o...

The impact of waves and bores generated by broken solitary waves on horizontal decks of coastal structures was studied by solving the Navier–Stokes equations. Solitary waves of different amplitudes were considered, and submerged ramps were used to bring the waves to the breaking point. The horizontal fixed deck was located downwave of the ramp and...

Water current interaction with arrays of plates is studied by use of the computational fluid dynamics focusing on hydrokinetic energy production applications. Various configurations of arrays of equidistant rectangular plates are considered and the current-induced pressure and velocity distribution, and the hydrodynamic forces on the individual pla...

This study is concerned with the generation and propagation of strongly nonlinear waves in shallow water. A numerical wave flume is developed where nonlinear waves of solitary and cnoidal types are generated by use of the Level I Green-Naghdi (GN) equations by a piston-type wavemaker. Waves generated by the GN theory enter the domain where the flui...

At present, studies on large-amplitude internal solitary waves mostly adopt strong stratification models, such as the two-and three-layer Miyata—Choi—Camassa (MCC) internal wave models, which omit the pycnocline or treat it as another fluid layer with a constant density. Because the pycnocline exists in real oceans and cannot be omitted sometimes,...

Diffraction and refraction of nonlinear shallow water waves due to uneven bathymetry are studied by use of the Green-Naghdi (GN) equations in two and three dimensions. A numerical wave tank consisting of deep, transitional and shallow regions is created. Various forms of three-dimensional bathymetry, consisting of ramps with nonuniform profiles and...

Interaction of linear and nonlinear, long-crested waves with currents in deep and finite water depths is studied by use of the computational fluid dynamics approach. Various wave conditions are considered by systematically changing the wave height and the wavelength. Several current profiles are studied as polynomial functions of water depth follow...

Effect of various forms of currents on regular nonlinear waves in shallow water is investigated by use of a computational fluid dynamics approach. A range of wave conditions with different wave heights and wave periods are considered. Effect of three types of currents on these waves is investigated, namely (i) uniform current over the water depth,...

Wave-induced oscillations of submerged horizontal plates are studied by conducting laboratory experiments and by developing theoretical and computational models. These models include a linear solver based on the Green-function method, a nonlinear model based on Green–Naghdi wave equations, and a model based on computational fluid dynamics. The subm...

Parametric resonance is a phenomenon caused by time-varying changes in the parameters of a system which may result in undesirable motion responses and instability. Floating bodies like ships and spar-buoys are prone to Mathieu instability mainly due to the instantaneous change of the metacentric height. With the fast-growing developments in Ocean R...

Diffraction and refraction of nonlinear shallow water waves due to uneven bathymetry is studied numerically in two and three dimensions. The numerical tank consists of a wavemaker at the upwave side of the domain, the submerged obstacles in the middle of the domain, and a numerical wave absorber on the downwave of the domain. The numerical wavemake...

Water current interaction with a hydrokinetic energy converter is studied by use of computational fluid dynamics. Mass of water turbine (MOWT) consists of several thin paddles attached to a conveyor, that are allowed to rotate around the hull. As the incoming current passes under the current energy converter, the paddles move to the direction of th...

Exercise-induced laryngeal obstruction is a paradoxical laryngeal closure during inspiration at high-intensity exercise, with supraglottic closure being most common. This study develops a model based on the computational fluid dynamics to investigate airflow velocity and pressure and the air-induced loads on the supraglottis at various inspiratory...

A multi-unit floating offshore wind turbine concept, the wind-tracing floating offshore wind turbine, is introduced. In this concept, the floating structure is a triangular platform that hosts three 5 MW wind turbines and is moored to the seabed with a turret-bearing mooring system. This mooring system allows the structure to rotate about the turre...

A nonlinear theoretical model for deformations, oscillations, and drift motions of multiple elastic ice sheets in shallow waters due to combined nonlinear waves and uniform current is presented. The model is based on the Green–Naghdi theory for the fluid motion and the thin plate theory for the deformation of the ice sheets. In principle, there are...

Bore impact on horizontal fixed decks of coastal structures is studied by use of the Level I Green-Naghdi (GN) equations and the Navier-Stokes (NS) equations. The bore is generated by the breaking of a water reservoir, and may represent the propagation of a tsunami on land or broken storm waves. The bore-induced horizontal and vertical forces are d...

The drift motion of a freely floating deformable ice sheet in shallow water subjected to incident nonlinear waves and uniform current is studied by use of the Green–Naghdi theory for the fluid motion and the thin plate theory for an elastic sheet. The nonlinear wave- and current-induced forces are obtained by integrating the hydrodynamic pressure a...

This study is concerned with hydroelastic interaction of water waves with a fully-submerged wave energy device. The oscillating component of the submerged energy device is a circular, horizontal disc. Wave interaction with the horizontal disc results in formation of time-dependent pressure differential above and below the disc, and consequently a p...

Hydroelastic responses of floating elastic surfaces to incident nonlinear waves of solitary and cnoidal type are studied. There are N number of the deformable surfaces, and these are represented by thin elastic plates of variable properties and different sizes and rigidity. The coupled motion of the elastic surfaces and the fluid are solved simulta...

The weakly nonlinear wavefront results of HLIGN equations are compared with linear analytical solutions and good agreement is achieved. The strongly nonlinear wavefront results of HLIGN equations in different water depths are presented, the water depth effects and the nonlinearity effects on the water wavefront are investigated.

Experimental and numerical studies on internal solitary waves with a free surface - Volume 899 - Binbin Zhao, Zhan Wang, Wenyang Duan, R. Cengiz Ertekin, Masoud Hayatdavoodi, Tianyu Zhang

Structural integrity has remained a challenge for design and analysis of wave energy devices. A difficulty in assessment of the structural integrity is often laid in the accurate determination of the wave-induced loads on the wave energy devices and the repones of the structure. Decoupled hydroelastic response of a submerged, oscillating wave energ...

Experiments are conducted on the mode 1 and mode 2 internal solitary waves in strong density stratification for a three layer fluid system with free su rface H ig h Level Green Naghdi ( HLGN equations are u sed to study this problem. Results of the HLGN equations are compare with the laboratory experiments, and with other available data. Results of...

In this paper, steady solutions of solitary waves in the presence of nonuniform shear currents are obtained by use of the high-level Green-Naghdi (HLGN) model. We focus on large-amplitude solitary waves in strong opposing shear currents. The linear-type currents, quadratic-type currents and cubic-type currents are considered. In particular, the wav...

Propagation and impact of two and three dimensional bores generated by breaking of a water reservoir is studies by use of three theoretical models. These include the Reynolds-Averaged Navier-Stokes (RANS) equations, the Level I Green-Naghdi (GN) equations and The Saint-Venant (SV) equations. Two types of bore generations are considered, namely (i)...

Wind energy industry is expanded to offshore and deep water sites, primarily due to the stronger and more consistent wind fields. Floating offshore wind turbine (FOWT) concepts involve new engineering and scientific challenges. A combination of waves, current, and wind loads impact the structures. Often under extreme cases, and sometimes in operati...

Most of the existing floating offshore wind turbines (FOWT), whether in concept or built, host a single turbine. Structures that can host multiple turbines have received attention in recent years, mainly with the aim of reducing the overall cost of energy production and maintenance. A concept challenge of placing multiple wind turbines on a single...

We use the Level II Irrotational Green–Naghdi (IGN-2) equations to study a number of wave diffraction problems. The IGN-2 equations can model strongly nonlinear waves. The three-dimensional solution of the IGN-2 equations is developed in this work and applied to some three-dimensional wave transformation and diffraction problems. Three test cases a...

This study is concerned with laboratory experiments of interaction of nonlinear water waves with submerged, oscillating bodies in shallow water. Due to the propagation of surface waves, time-dependent pressure differential is formed above and under the submerged body. This pressure differential results in oscillatory vertical force on the body. A v...

This study is concerned with motion analysis and hydroelastic response of a floating offshore wind turbine to wave loads. The novel floating structure, made of prestressed concrete, is designed to support multiple wind turbines, and it rotates according to the environmental loads to face the incoming wind. The floating structure is attached to a mo...

Bores generated by dam-break and initial mound of water and their propagation over horizontal and inclined surfaces are studied by use of theoretical approaches. Calculations are carried out in two and three dimensions and particular attention is given to the bore impact on horizontal and vertical surfaces. Downstream of the initial mound of water...

This study is concerned with calculations of nonlinear wave loads on submerged, horizontal decks in shallow water. Solitary and cnoidal wave loads on submerged decks are determined by use of the Level I Green–Naghdi (GN) equations. Results of the GN equations are compared with the linear theory, CFD, and with available laboratory measurements. Vari...

Diffraction of nonlinear water waves by floating ice sheets in marginal ice zones is studied by use of the Level I Green-Naghdi equations and by Reynolds-Averaged Navier-Stokes equations. In general, there are N number of compact and deformable ice sheets of arbitrary size. Particular attention is given to the wave-induced loads on the ice sheets a...

Diffraction of nonlinear waves by single or multiple in-line vertical cylinders in shallow water is studied by use of different nonlinear, shallow-water wave theories. The fixed, in-line, vertical circular cylinders extend from the free surface to the seafloor and are located in a row parallel to the incident wave direction. The wave–structure inte...

This study is concerned with the diffraction of nonlinear waves by in-line, fixed, vertical, circular cylinders in shallow water. The solitary and conical wave-structure interaction problem is studied by use of the nonlinear Level I Green-Naghdi equations and the nonlinear generalised Boussinesq equations. The problem is also solved by the lineariz...

The interaction of solitary waves with multiple, in-line vertical cylinders is investigated. The fixed cylinders are of constant circular cross section and extend from the seafloor to the free surface. In general, there are N of them lined in a row parallel to the incoming wave direction. Both the nonlinear, generalized Boussinesq and the Green–Nag...

Solitary and cnoidal wave transformation over a submerged, fixed, horizontal rigid plate is studied by use of the nonlinear, shallow-water Level I Green-Naghdi (GN) equations. Reflection and transmission coefficients are defined for cnoidal and solitary waves to quantify the nonlinear wave scattering. Results of the GN equations are compared with t...

Preliminary conceptual design of a submerged wave energy converter (WEC) device in shallow water is presented. The WEC consists of a fully submerged, horizontal, flat plate that is restricted to vertical oscillations due to surface waves. Thin rails are used to guide the vertical oscillations and restrict the motion in all other directions. The ver...

Highlights • Interaction of nonlinear shallow-water waves with an elastic submerged plate is studied. • The nonlinear wave-structure problem is modeled by use of the coupled Level I Green-Naghdi equations and the thin, elastic-plate theory. • A submerged elastic plate can function as a wave carpet for high-performance wave energy harvesting, or for...

Recent natural extreme events, such as Hurricane Ike in the US (2008), Tohoku tsunami in Japan (2011), and Typhoon Haiyan in Southeast Asia (2013), have caused significant damage to decks of coastal bridges. The failure of the structure occurs when wave-induced loads on decks of coastal bridges exceed the bridge capacity, resulting in partial remov...

Hydrodynamic analysis of oscillation of a submerged plate due to nonlinear shallow water waves is studied. The submerged oscillating plate is the core component of a submerged wave energy converter. A concept design of the wave energy converter located in shallow water is presented. The device utilizes the heave motion of the submerged plate for wa...

A horizontal submerged plate is located in shallow water, and can oscillate in the vertical direction due to the propagation of nonlinear waves. Interaction of the waves with the oscillating plate is studied by use of the Level I Green-Naghdi equations. The nonlinear oscillation of the plate is determined by solving the equation of vertical motion,...

Vulnerability assessment of four selected prototype coastal bridges on the island of Oahu, Hawaii, to the combination of storm surge and waves is presented. The maximum storm surge condition is estimated by considering an extensive series of simulated hurricanes making landfall on the island of Oahu, where the bridges are located. For the given ext...

Horizontal and vertical forces on a 1:35 scale model of a typical two-lane coastal bridge due to cnoidal wave loads are investigated by conducting an extensive set of laboratory experiments and comparing the resulting data with CFD calculations and existing simplified, design-type equations. The experimental parameters tested cover a wide range of...

Wave forces on coastal-bridge decks are calculated by Euler's equations, and by nonlinear shallow-water wave equations. Euler's equations are solved by use of an open source Computational Fluid Dynamics (CFD) software, namely OpenFOAM. In the numerical wave tank, Euler's equations are solved for both water and air above, and the free-surface is det...

The Green–Naghdi (GN) wave models are categorized into different levels based on the assumptions made for the velocity field. The low-level GN model (Level I GN model or called the GN-1 model) is a weakly dispersive, strongly nonlinear wave model. As the level goes up, the high-level GNmodel becomes a strongly dispersive, strongly nonlinear wave mo...

Wave forces on coastal-bridge decks are calculated by Euler’s equations, and by nonlinear shallow-water wave equations. Euler’s equations are solved by use of an open source Computational Fluid Dynamics (CFD) software, namely OpenFOAM. In the numerical wave tank, Euler’s equations are solved for both water and air above, and the free-surface is det...