Carlos Guedes Soares

University of Lisbon | UL · Centre for Marine Technology and Ocean Engineering (CENTEC)

A numerical hydrodynamic model for a moored interconnected floating large structure under the action of regular waves is presented to analyze the effect of current and wind. The floating structure consists of 20 hinged plates that are linked together and secured with mooring lines along its edges. A brief discussion is provided on the multi-body hy...

An analytical model of wave-current interaction with a moored floating circular structure has been developed using Timoshenko-Mindlin beam theory. The analytical solution is derived utilising the matched eigenfunction expansion method, combined with orthogonal relations and Bessel functions. The convergence study of the analytical solution for diff...

A low-cost stereo vision technique is presented to estimate the ocean wave field in space and time. The method costs only about 1% of traditional instruments for wave measurements and is even cheaper and easier to implement than typical stereo video techniques. Despite the system providing lower-resolution data than higher-grade stereo video system...

Spatial variation of nonlinear wave groups with different initial envelope shapes is numerically studied by the nonlinear Schrödinger (NLS) equation, confirming that the simplest nonlinear theoretical model can describe the evolution of propagating wave packets reasonably well in deep water. Moreover, three groups of laboratory experiments run in t...

The evolution of Gaussian wave packets is theoretically studied under different kinds of governing equations, and the critical asymmetric features of propagating wave packets can be effectively captured by the higher order nonlinear Dysthe model. Moreover, laboratory experiments run in an offshore wave basin are systematically compared with a large...

Fully nonlinear numerical simulations performed with the HOS method reveal that Peregrine breather solution has a high probability to persist even in a chaotic environment and that the maximum amplification factor of such breather dynamics can be larger than the theoretical prediction in the regular background wave. The maximum wave height attainab...

The fully nonlinear Chalikov-Sheinin (CS) model, based on a nonstationary conformal surface following coordinate transformation that reduces the principal equations of potential waves into two simple evolutionary equations, is firstly used to study the dynamics of nonlinear gravity waves, mainly involving the propagation of Stokes wave with disturb...

The prototype of extreme wave, named as Kuznetsov-Ma breather solution has been tested in a seakeeping wave tank with different initial wave steepness and water depths. The laboratory observations can be accurately simulated by the high-order spectral model (HOS) if the initial Benjamin-Feir index is not very large, i.e. weak nonlinearity and/or sm...

The laboratory experiments performed in two different wave basins are comparatively analysed with both spectral and statistical methods to verify and validate the wave data used in the following numerical study. Comparison has been made in the aspects of the main sea state parameters, the power spectral density, the joint distribution of wave heigh...

The temporal and spatial evolutions of nonlinear wave groups with different initial steepness are numerically studied under the governing of MNLS equations. It reveals that due to the slight discrepancy in the dispersion relationship, the temporal and spatial versions of numerical model are not always consistent in the whole evolution process, part...

The new methodology based on generalised coordinates for the analysis of floating multi-body systems with nonlinear geometric constraints is developed, and it is demonstrated through numerical application for a hybrid floating wind-wave platform consisting of a floating offshore wind turbine and an articulated wave energy converter that moves a hyd...

The present review paper focuses on the recent developments in the multi-body large floating structures based on theoretical, numerical, and experimental research applications in offshore regions for ocean space utilization. Initially, a brief overview of the modelling approaches of the analytical and numerical methods for multi-body floating syste...

Environmental perception is crucial for autonomous ships realizing autonomous navigation, in particular, the high-precision and low-latency detection of small objects on the sea surface is a key and challenging issue. To address this problem, this paper presents a model that improves the detection accuracy and delivers excellent real-time performan...

This paper presents a theoretical model for oblique wave interaction with an integrated wave energy system that combines a box-type heaving buoy wave energy converter (WEC) and a vertical flexible perforated membrane (VFPM) wall. The formulation is modeled based on the linear water wave theory and utilises the Fourier expansion along with the eigen...

A two-dimensional analytical model is developed to study the hydroelastic response of a multi separated moored floating circular module in finite water depth. This mathematical formulation is based on the linearised small amplitude and structural response, whilst the floating module is modeled as the Timoshenko-Mindlin-Beam theory. By considering t...

Extended details of the journal paper entitled: A review on wave energy resource characterization, metrics, and global assessments. This is a preprint version. The final publication is available at https://doi.org/10.1007/s11804-024-00545-9

This paper provides an overview of the global characterization of wave energy resources for exploration. The most popular metrics and estimators for wave energy resource assessment have been compiled and classified by levels of energy exploitation. A review of existing prospective wave energy resource assessments worldwide is also given, and those...

A novel Maritime Multi-Object Tracking method is proposed, combining a deep learning-based object detector with target association algorithms to achieve robust sea-surface multi-object tracking. Specifically, the Multi-Object Tracking employs You Only Look Once version 7 detector for object detection. In the data association part, a module for onbo...

A Boussinesq model associated with surface and internal waves with surface tension and interfacial tension in a two-layer fluid is presented in the application range of weakly dispersive nonlinear. The nonlinear form of model definitions in terms of surface and interfacial tensions along with velocity potentials are provided. Based on the perturbat...

This study proposes a novel and feasible framework for assessing maritime traffic complexity, utilising historical Automatic Identification System data to extract dynamic traffic characteristics of sea waters and quantify the corresponding maritime traffic complexity. The processed historical statistics are initially segmented into subsets accordin...

A novel framework for predicting the hydrodynamic performance of autonomous underwater vehicles (AUVs) is proposed based on computational fluid dynamics (CFD) and physics-informed generative adversarial networks (PIGAN). The physics information is embedded in the generator and discriminator, improving prediction accuracy and efficiency. The antenna...

The present review focuses on the theoretical model developments made in floating flexible net fish cages and the floating bodies application to offshore aquaculture. A brief discussion of the essential mathematical equations related to various theoretical models of flexible net cages in the frequency domain is presented. The single and array of fl...

This study presents an optimisation-based approach for determining controller gains in ship path-following under varying sea states, wave, and wind directions. The dynamic Line of Sight approach is used to regulate the rudder angle and guide the Esso Osaka ship along the desired path. Gains are optimised using a genetic algorithm and a comprehensiv...

This paper presents an overview of the recent developments in hybrid wind-wave energy. With the focus on floating concepts, the possible configurations introduced in the literature are categorized and depicted, and the main conclusions obtained from the references are summarized. Moreover, offshore wind and wave resources are discussed in terms of...

The uncertainty in estimating the wave spectrum from the records of wave elevation by heave-pitch-roll buoys is studied, considering the effects of the estimation method and the spectral resolution adopted in the process. This investigation utilizes measurements from a wave buoy moored in deep water in the South Atlantic Ocean. First, the spectra a...

A set of planar motion mechanism experiments of the Duisburg Test Case Post-Panamax container model executed in a towing tank with shallow depth is applied to train a neural network to analyse the ability of the proposed model to learn the effects of different depth conditions on ship’s manoeuvring capabilities. The motivation of the work presented...

This paper is dedicated to correcting the WAM/ICON numerical wave model predictions by reducing the residue between the model’s predictions and the actual buoy observations. The two parameters used in this paper are significant wave height and wind speed. The paper proposes two machine learning models to solve this task. Both models are multioutput...

A 3D analytical model is formulated based on linearised small-amplitude wave theory to analyse the behaviour of a horizontal, flexible membrane subject to wave–current interaction. The membrane is connected to spring moorings for stability. Green’s function approach is used to obtain the dispersion relation and is utilised in the solution by applyi...

A review of multi-chamber oscillating water column (OWC) device designs is presented. Two significant variations of these devices are discussed, onshore OWC (OOWC) and a floating OWC (FOWC). The efficiency results of several theoretical studies based on low- and high-fidelity numerical models are presented and compared with the model scale results....

This paper proposes an intelligent failure data analysis framework to identify failure features of wind turbines intelligently and automatically, requiring few interactions with analysts. Initially, two operation and maintenance datasets in terms of wind turbine failure and maintenance onshore (LGS-Onshore) and offshore (LGS-Offshore) are introduce...

This paper aims to investigate the impact of controller parameters on the performance of a PID controller in the maneuvering of two ships. In present work, a maneuvering model, which accounts the hydrodynamic interactions, is established using the MMG model. The shallow water effects on hydrodynamic derivatives are estimated by empirical formulas,...

Floating platforms equipped with multiple moonpools offer tremendous potential for applications in advanced offshore aquaculture. This paper investigates the hydrodynamics of a floating platform equipped with multiple moonpools, highlighting their promising applications in advanced offshore aquaculture. Utilizing an in-house linear potential-flow s...

For making a protective structure, the AL6XN steel has high ductility and excellent strength, and in the current study, it is used for making protective structures. The present work deals with a cost-effective numerical analysis of the protective structures’ blast performance. To investigate the significant effects on the air blast mitigation of a...

The behavior of a chemical tanker (CT) in extreme waves was discussed in detail, that is, in terms of rigid body heave and pitch motions, vertical bending moments (VBMs) amidships, green water, and slamming impacts through the analysis of the experimental data from model tests. Regular wave tests conducted for two wave steepness showed that the inc...

Enhancing the precision of short-term mooring tension prediction holds the key to bolstering safety measures within marine operations. In this study, a hybrid model which takes the advantages of convolutional neural networks (CNN) and gated recurrent units (GRU) is developed to predict dynamic mooring tension time series of a wave energy converter....

This study investigates scale effects on hydrodynamics of a 2D submerged circular cylinder subjected to incoming flow in Computational Fluid Dynamics simulation. The primary focus is the influence of varying scale ratios on drag coefficient, lift coefficient, and vortex shedding frequency in high Reynolds number conditions. The methodology involves...

The maritime industry faces many pressing challenges due to increasing environmental and safety regulations and crew safety concerns [...]

This paper presents the theoretical investigations on the free and forced vibration behaviours of carbon/glass hybrid composite laminated plates with arbitrary boundary conditions. The unknown allowable displacement functions of the physical middle surface are expressed in terms of standard cosine Fourier series and sinusoidal auxiliary functions t...

This paper aims to study the higher-harmonics wave-induced surge force on the CENTEC-TLP platform in regular head waves with non-breaking assumptions, using a CFD-based numerical wave tank model, which is a useful tool for the analysis of the nonlinear interaction of waves and structures. Moreover, the influence of change in the wave diffraction an...

This study proposes explicit approaches for modelling ship structural loads including the temporal correlation of wave-induced load cycles. The available methods for ship structural load modelling are critically reviewed. The correlated wave-induced loads in each sea state are modeled using the stochastic Markov process and a closed-form formulatio...

The paper proposes a fleet size and mix vehicle routing model to optimize the river-sea liner shipping service. A mixed integer linear programming model is adopted as a rapid screening tool for strategic fleet planning to determine the type and number of river-sea vessels to deal with the fluctuation of the demand over the year, guaranteeing the ef...

The Burr distribution is adopted to model the environmental contours along the Portu-guese continental coast using the Inverse-First Order Reliability Method. The resulting final contours constructed considering the Burr-Lognormal as a probabilistic model are compared with the contours constructed with Generalised Extreme Value-Lognormal distributi...

The uncertainty evaluation of a direct method to derive environmental contours is stated. The characterization of the environmental observations at sea is computed due to the sample variability leading to the important sources of uncertainty. The sample variability is based on 5, 10 and 15 years of sample for location A and 1, 5 and 25 for location...

As the impact of fossil fuels on the planet becomes clear, the world is increasingly focusing on renewable energy sources [...]

An overview is provided of the different approaches used for the wave energy characterization , and of the existing wave energy resource levels along the European continental coasts. Studies are classified by basins, regional seas, and countries. Most energetic areas all over Europe are highlighted and discussed. Main outcomes indicate that a compl...

A numerical model is built to study the performance of gravity cages on the coast of Algarve. A review is made of the situation in Portugal concerning offshore aquaculture and the areas in Algarve that are planned for this activity are identified. From the previous study, the high-tenacity polyester multifilament fibre has excellent performance for...

Based on the energy transition plans of the Canary Islands archipelago towards a more sustainable and self-sufficient electricity system, this research assesses the optimal configuration of a hybrid stand-alone grid system for the Canary Islands that attains 100% renewable energy penetration, removing fossil fuel reliance and boosting self-sufficie...

An overview of the state of the art of the floating photovoltaic renewable energy technology is given. The main characteristics of floating photovoltaic systems are outlined, as well as the features influencing on their preformance. Moreover, existing concepts and ongoing projects around the world are compiled and briefly described. The advantages,...

To determine the capabilities of long short-term memory (LSTM) neural networks to extend the skill of wave forecasts, the ERA5 hindcast database is used as a test case. Data from a buoy located in the North Atlantic Ocean near Portugal continental coast is used as the reference value. The error between the ERA5 data set and the wave buoy records is...

The performance of a dual submerged horizontal flexible membrane breakwater is analysed analytically. The mathematical model for oblique wave interaction with the membrane breakwater is established based on the linearized potential flow theory and the assumption of small amplitude structural response. The analytical solution is obtained using the m...

Drawing upon linear potential flow theory, a numerical model of wave interaction with a moored articulated large floating flexible structure is presented. The floating flexible structure is combined by six plates with hinges and connected with mooring lines at its edges. The mathematical equations associated with the numerical model formulations an...

Under linearized small amplitude water wave theory and structural response, an analytical model associated with effect of a moored floating flexible circular structure under Timoshenko-Mindlin beam theory is developed. The theoretical solution is obtained by matched eigenfunction expansion method along with orthogonal relation and Bessel’s function...

The objective of this study is to compare the accuracy in predicting waves in coastal areas of the Wavewatch3 model, which has been used mostly for deep waters, with the SWAN model, which is often used close to the coasts. The wave conditions in the target area, the coastal area of Figueira da Foz, located at the center of Portugal’s continental co...

Two conventional, low-cost action cameras with a freeware synchronization technique are used to estimate the time-varying three-dimensional sea surface elevation map and its associated wave number frequency spectrum. Spatio-temporal measurements in very shallow water are conducted with the cameras and are validated with a moored pressure sensor as...

The study investigates the behaviour of a liquified natural gas carrier in regular head waves using the Smoothed Particle Hydrodynamics meshfree method implemented in DualSPHysics. A numerical wave tank in three-dimensional domain is generated using the modified Dynamic Boundary Conditions and compared with the theoretic wave surface using Stokes e...

In this work, the hydrodynamics forces on semi-submerged and submerged cylinders under a steady flow are analysed using the numerical code DualSPHysics, which implements the Smoothed Particle Hydrodynamics (SPH) method. The published experimental tests which were conducted in the Shanghai Ship and Shipping Research Institute, for submerged and semi...