Rodolfo Trentin Gonçalves

The University of Tokyo | Todai · Department of Systems Innovation

The continuous monitoring of sea states is important for many activities, from gathering oceanographic data to the planning of ship operations. There are several means to infer sea conditions, with variable levels of accuracy. Among these, the methods based on on-board measurements of vessel motions have been addressed by many researchers, attracte...

The vortex-induced motions (VIM) is a phenomenon that can promote large oscillatory amplitudes on circular platforms in the horizontal plane, such as spar or monocolumn production, storage, and offloading system (MPSO). Floating offshore wind turbines (FOWT) can use a spar-type platform to support the turbine, and due to the wind incidence, roll or...

The flow around a circular section has many applications in engineering, specifically in the offshore area, such as platforms, risers, pipelines, etc. These structures, which are submerged in water, are susceptible to flow-induced vibrations (FIV) and might oscillate at unwanted large amplitudes due to currents and waves. The Computational Fluid Dy...

This paper presents the flow-induced forces over 3-column arrays with different cross-sectional geometries due to the current incidence only, using Computational Fluid Dynamics (CFD) calculations for a low Reynolds number (\(\mathrm{Re}\)). The flow around circular, square, and diamond sections of 3-column arrays was evaluated for stationary condit...

The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a Floating OffshoreWind Turbine (FOWT) with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loa...

A tank experiment using a flexible multi-column floating offshore wind turbine (FOWT) model in regular waves was carried out to clarify the floater elastic response and its influence on the floater motion. The model motion response from the experiment was compared with the numerical simulations by NK-UTWind and WAMIT codes. The dynamic elastic defo...

A shallow draft cylindrical barge type floater with footing close to the water surface was experimentally evaluated in waves to investigate non-linear motion characteristics. The floater was designed to be used as an option for FOWT—floating offshore wind turbines. The non-linear mechanism can be promoted due to the viscous force that acts on the f...

The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a FOWT with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loads during the tests. A set of wa...

Aiming to complete the results presented before in Gonçalves et al. (2012. Ocean Eng. 54, 150-169) and Gonçalves et al. (2013. Ocean Eng. 62, 10-24), this third part of the research work studied the behavior of large-volume SS - semi-submersible platforms due to the VIM - vortex-induced motions under the combined action of current and waves. Small-...

Flow-induced motions (FIM) can cause fatigue damage to the mooring and riser systems of deepwater offshore structures, especially for cylindrical platforms, such as Tension Leg Platform(TLP). Previous experimental and numerical studies have showed conservative FIM prediction compared to the field measurements, due to many significant factors such a...

A floating offshore wind turbine (FOWT) concept with a guy-wire-supported tower was investigated to obtain motion results in waves considering its elastic model characteristics. The FOWT concept studied aims to reduce the construction costs by using a light-weight structure tensioned with guy wires and a downwind type. Wave tank experiments of an e...

Experiments regarding vortex-induced motions (VIM) of floating circular cylinders with low aspect ratio, / = 2.0, and different heave plate configurations were carried out in a recirculation water channel; where is the diameter and is the submerged length of the cylinder. The floating circular cylinders were elastically supported by a set of linear...

Dear Colleagues, Offshore wind energy is one of the largest renewable sources, and a considerable amount of wind energy is located further offshore in deeper waters. Due to the limitation of using bottom-mounted offshore wind turbines for water depths larger than 60 m, wind turbines placed on floating platforms are being investigated as a potentia...

Flow-Induced Motions (FIM) are an issue for floating offshore structures, such as multi-column platforms, as the phenomenon can decrease the fatigue life of the mooring, riser, and cable systems. The new concept of Floating Offshore Wind Turbines (FOWT) have a multi-column design that may be subjected to FIM. In the past, FIM was studied mainly for...

The Flow-Induced Motions (FIM) is an essential topic on multi-column platforms due to the effect on the mooring line fatigue life. Vortex-Induced Motions (VIM) or galloping behavior can be observed for an array of four columns with square sections. The presence of pontoons showed to be important for changing the flow around the array and promoting...

A floating offshore wind turbine (FOWT) concept with a guy wire-supported tower was investigated to obtain results of motion in waves considering its elastic model characteristics. The FOWT concept aims to reduce construction costs by using a light-weight structure tensioned with guy wires and a downwind turbine concept type. A wave tank experiment...

A floating offshore wind turbine (FOWT) concept with a guy wire-supported tower was investigated to obtain results of motion in waves considering its elastic model characteristics. The FOWT concept aims to reduce construction costs by using a light-weight structure tensioned with guy wires and a downwind turbine concept type. A wave tank experiment...

The Flow-Induced Motions (FIM) is an essential topic on multi-column platforms due to the effect on the mooring line fatigue life. Vortex-Induced Motions (VIM) or galloping behavior can be observed for an array of four columns with square sections. The presence of pontoons showed to be important for changing the flow around the array and promoting...

The choice of drag and inertia coefficients are critical for the evaluation of hydrodynamic loads in slender cylinders using either Morison's equation or an approach where viscous forces are simply added to the results of potential theory. Many studies available in the literature have considered fixed cylinders under the action of (two dimensional)...

In this study, a numerical prediction model for vortex-induced motions (VIM) of 4-circular-column floater was developed from a database of hydrodynamic forces acquired from the forced oscillation tests. A set of combinations of oscillation frequencies and amplitudes in the transverse direction (1 degree of freedom) were carried out. The numerical r...

Experiments regarding the flow-induced motion (FIM) on an array of three floating cylinders with low aspect ratio (H/L=1.5), and three different distances between column centers (S/L= 2, 3, and 4) were carried out in a towing tank. The array of three cylinders was elastically supported by a set of four linear springs to provide low structural dampi...

This paper presents an analysis of the effects of heave plates with large skirts on the dynamics of a semi-submersible FOWT in waves. The analysis was based on a preliminary hull configuration envisaged for Brazilian waters. A numerical model based on linear frequency-domain hydrodynamics evaluated with panel methods was used for predicting the eff...

A floating offshore wind turbine (FOWT) concept with a guy wire supported tower was investigated to obtain results on its elastic response characteristics in waves and winds. The concept aim is to reduce the cost of FOWTs by using a lightweight structure tensioned with guy wires and a downwind turbine concept. Thereby, the whole floater is a weathe...

The vortex-induced motions (VIM) is a phenomenon that can promote large oscillatory amplitudes on circular platforms in the horizontal plane as spar or monocolumn ones. Floating offshore wind turbines (FOWT) can use a spar type platform to support the turbine, and due to the wind incidence, roll or pitch angles can occur. The goal was to investigat...

In the present paper, an analysis of the use of heave plates with large skirts is presented. The work is developed in the context of the conception of a FOWT designed to operate in Brazilian waters, collaborative research being conducted by the University of São Paulo and the University of Tokyo. The preliminary version of the hull consists of four...

Flow-Induced Motions (FIM) is an issue for multi-column platforms, and the phenomenon can decrease the fatigue life of the mooring, riser, and cable systems. In the past, FIM was studied mainly for platforms installed in deep waters. The new concepts of Floating Offshore Wind Turbines (FOWT) have multi-column design and may therefore observe FIM. H...

Flow-Induced Motions (FIM) is an issue for multi-column platforms, and the phenomenon can decrease the fatigue life of the mooring, riser, and cable systems. In the past, FIM was studied mainly for platforms installed in deep waters. The new concepts of Floating Offshore Wind Turbines (FOWT) have multi-column design and may therefore observe FIM. H...

The flow-induced motions (FIM) of platforms is a vital phenomenon issue to be investigated to help the designers and to decrease the costs related to the mooring and/or riser systems. On this matter, when talking about multi-column configurations, captive tests (also called fixed or stationary tests) can be a methodology worth of examining the vort...

Experiments were carried out in a recirculating water channel regarding the flow around stationary circular cylinders with low aspect ratio and different free-end corner shapes piercing the water free surface. Four different aspect ratios, L/D, were tested as, 0.3, 0.5, 1.0, and 2.0, where L is the submerged length of the cylinder and D is the diam...

Hydrodynamic forces in the streamwise and the transverse directions were measured in a towing tank on stationary and half-submerged cylinders with low aspect ratio aiming at understanding the free-surface effects. Since the Froude number mainly characterizes the movement of the free-surface, different circular cylinders with different diameters wer...

An experimental campaign for the flow around a stationary array of three and four columns with low aspect ratio, H/L=1.5, piercing the water free surface, was carried out in a towing tank. These numbers of columns correspond to typical multi-column offshore systems, such as semi-submersibles (SS), tension leg platforms (TLP) and floating offshore w...

The Flow-Induced Motions (FIM) of multi-column platforms is a vital behavior mainly for the fatigue life of mooring line systems. Suppressing the FIM is a way to increase the life of the mooring systems and consequently decreases the costs of the project. The vortex shedding around the columns is the key to understand the forces that promote large...

The Flow-Induced Motions (FIM) is an essential topic on multi-column platforms due to the effect on the mooring line fatigue life. Vortex-Induced Motions (VIM) or galloping behavior can be observed for an array of four columns with square sections. The presence of pontoons showed to be important for changing the flow around the array and promote di...

The Flow-Induced Motions (FIM) of multi-column platforms is a vital behavior mainly for the fatigue life of mooring line systems. Suppressing the FIM is a way to increase the life of the mooring systems and consequently decreases the costs of the project. The vortex shedding around the columns is the key to understand the forces that promote large...

The Flow-Induced Motions (FIM) is an essential topic on multi-column platforms due to the effect on the mooring line fatigue life. Vortex-Induced Motions (VIM) or galloping behavior can be observed for an array of four columns with square sections. The presence of pontoons showed to be important for changing the flow around the array and promote di...

Studies about the flow around single column are the preliminary way to understand the behaviour of multi-column systems, e.g. semi-submersible platforms and floating offshore wind turbines. The presence of a rounded edge in a square column can include advantages in the constructive phases, on the other hand, can include difficulty in understanding...

The majority of wave energy devices operate close to resonant conditions to enhance energy conversion resulting in large displacements. As a result, nonlinearities significantly contribute to the dynamics of the system. A typical approach to predict the behavior of the system and power output relies on the derivation of a mathematical model in the...

Studies about the flow around single column are the preliminary way to understand the behaviour of multi-column systems, e.g. semi-submersible platforms and floating offshore wind turbines. The presence of a rounded edge in a square column can include advantages in the constructive phases, on the other hand, can include difficulty in understanding...

The effect of wake interaction on the hydrodynamic force was experimentally investigated. A scaled platform model with four columns was subjected to a current in the circulating water channel with constant velocity. The diameter of each column was 75 mm, and the aspect ratio (defined by the ratio between the column draft and diameter) was 1.5. The...

Wave energy converters (WECs) are often subject to large displacements during operating conditions. Hence, nonlineari-ties present in numerical methods to estimate the performance of WECs must be considered for realistic predictions. These large displacements occur when the device operates on resonant conditions , which results in maximum energy co...

To obtain fundamental knowledge on the elastic response characteristics of a light-weight floating support structure of a FOWT (floating offshore wind turbine) with guywire supported tower, basic load transmission mechanism was investigated. Static analysis with elastic frame model, numerical analysis and wave tank experiment with elastically and d...

Floating offshore wind turbines (FOWT) have many pros and cons. Among the pros, we can mention the availability of more constant winds and a velocity more suitable to the use of turbines in their optimum efficiency. Among the cons, there are the high costs for installation, mooring lines and the large length of cables required for the energy transm...

The flow-induced motion (FIM) of platforms is an important issue to be investigated and require further investigation of captive models. On this matter, it is worth examining the vortex detachments, the source for the oscillatory lift, drag force and the interference of the upstream cylinders wake on the downstream ones. CFD calculations of the flo...

Floating structures with multi-column geometries such as semi-submersible offshore platforms and floating wind turbines might be subjected to flow-induced motions (FIM), which impacts mooring and other systems through complex fluid-structure interactions. More efficient and safe designs including prediction of that phenomenon in the early stages of...

The floater structure is responsible for one of the main costs of a floating offshore wind turbine (FOWT), leading to a large effort to reducing its structural weight in new designs. In this context, this paper describes the concept of a very light semi-submersible floater consisting of a central column, which sustains the tower, connected by ponto...

Wind energy is one of the most studied topics in the renewable energy scenario. In the last decades, the focus has been put on several aspects of modeling and analysis of onshore wind turbines. Particularly in Brazil, onshore wind energy has an enormous potential that has been investigated in some recent studies. In turn, floating offshore wind tur...

Experiments regarding vortex-induced vibration (VIV) on floating circular cylinders with low aspect ratio, 𝐿/𝐷 = 0.5, and different free-end conditions were carried out in a recirculation water channel. The floating circular cylinders were elastically supported by a set of linear springs to provide low structural damping on the system. Four differe...

Concern over the Vortex-induced Motions (VIM) acting on offshore structures, with special focus on monocolumn and spar platforms, mooring systems have crucial importance on system movements; the system has thus been transformed into a concept study herein. A floating and rigid circular cylinder with low aspect ratio (L/D=2) was used in the experime...

Experiments regarding vortex-induced vibration (VIV) on floating circular cylinders with low aspect ratio, L/D=0.5, and different free-end conditions were carried out in a recirculation water channel. The floating circular cylinders were elastically supported by a set of linear springs to provide low structural damping on the system. Four different...

A simple prediction model for VIM of multi-column floaters was developed. The model solved the one degree of freedom equation of motion which included inertia, damping, restoration and external force term. Inertia, damping and external force terms were obtained experimentally from measurements of forced oscillation tests with and without towing vel...

This research work aims to understand the behavior of large-volume semi-submersible platforms under the action of VIM and simultaneous wave incidence. VIM model tests with regular and irregular waves collinear to the current conditions were carried out to achieve the goals. The results showed that the waves influenced the phenomenon, although the n...

Experiments regarding the FIM - flow-induced motion on an array of three floating cylinders with low aspect ratio, 𝐻/𝐿 = 1.5, and three different distances between column centers, 𝑆/𝐿 = 2, 3 and 4, were carried out in a towing tank. The array of three cylinders was elastically supported by a set of four linear springs to provide low structural damp...