Felipe Ruggeri
University of São Paulo
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Featured researches published by Felipe Ruggeri.
Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme | 2015
Carlos Lopez-Pavon; Rafael A. Watai; Felipe Ruggeri; Alexandre N. Simos; Antonio Souto-Iglesias
The main focus of this paper is on hydrodynamic modelling of a semisubmersible platform (which can support a 1.5MW wind turbine and is composed by three buoyant columns connected by bracings) with especial emphasis on the estimation of the wave drift components and their effects on the design of the mooring system. Indeed, with natural periods of drift around 60 seconds, accurate computation of the low-frequency second-order components is not a straightforward task. As methods usually adopted when dealing with the slow-drifts of deep-water moored systems, such as Newman?s approximation, have their errors increased by the relatively low resonant periods, and as the effects of depth cannot be ignored, the wave diffraction analysis must be based on full Quadratic Transfer Functions (QTF) computations. A discussion on the numerical aspects of performing such computations is presented, making use of the second-order module available with the seakeeping software WAMIT®. Finally, the paper also provides a preliminary verification of the accuracy of the numerical predictions based on the results obtained in a series of model tests with the structure fixed in bichromatic waves.
ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering | 2013
Carlos Lopez-Pavon; Rafael A. Watai; Felipe Ruggeri; Alexandre N. Simos; Antonio Souto-Iglesias
AZIMUT project (Spanish CENIT R&D program) is designed to establish the technological groundwork for the subsequent development, of a large-scale offshore wind turbine. The project (2010–2013) has analysed different floating offshore wind turbines (FOWT): SPAR, TLP and Semi-Submersible platforms were studied. Acciona, as part of the consortium, was responsible of scale-testing a Semi-submersible platform to support a 1.5MW wind turbine. The floating platform geometry considered in this paper has been provided by the Hiprwind FP7 project and is composed by three buoyant columns connected by bracings. The main focus of this paper is on hydrodynamic modelling of the floater, with especial emphasis on the estimation of the wave drift components and their effects on the design of the mooring system. Indeed, with natural periods of drift around 60 seconds, accurate computation of the low-frequency second-order components is not a straightforward task. As methods usually adopted when dealing with the slow-drifts of deep-water moored systems, such as Newman’s approximation, have their errors increased by the relatively low resonant periods, and as the effects of depth cannot be ignored, the wave diffraction analysis must be based on full Quadratic Transfer Functions (QTF) computations. A discussion on the numerical aspects of performing such computations is presented, making use of the second-order module available with the seakeeping software WAMIT®. Finally, the paper also provides a preliminary verification of the accuracy of the numerical predictions based on the results obtained in a series of model tests with the structure fixed in bichromatic waves.Copyright
ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering | 2015
Felipe Ruggeri; Rafael A. Watai; Alexandre N. Simos
This paper presents a higher order time domain boundary elements method based on the Rankine sources for the computation of both linear and weakly non-linear effects for both fixed and free floating bodies. The geometry is described based on surfaces in a standard iges file, considering a NURBS (Non Uniform Rational Basis-Spline) description. The potential function, velocity, free-surface elevation and other quantities are defined using b-splines of arbitrary degree and the floating body interaction is solved using the potential acceleration approach on a Runge-Kutta scheme for time evolution. The integral equation is obtained and solved considering several possibilities for the collocation points, leading to an over-determined system. The integration over the panels is performed using a mixed desingularized-numerical method over Gaussian points. The results comparison are performed with WAMIT solution for a floating sphere concerning wave runup, body motions, velocity field, mean drift components in time domain.Copyright
ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering | 2014
Pasquale Dinoi; Rafael A. Watai; Hugo Ramos-Castro; Jesus Gómez-Goñi; Felipe Ruggeri; Antonio Souto-Iglesias; Alexandre N. Simos
Seakeeping behavior of a multibody system in side-by-side configuration in head sea condition is discussed in this paper. The system, which can be assimilated to a FLNG and LNG carrier during an offloading operation is composed of a barge and a prismatic geosim with two gap values. Seakeeping tests in regular waves have been performed in the model basin of CEHINAV-Technical University of Madrid (UPM). The movements for the geosim were restricted to the surge, heave and pitch motions (on the vertical plane), whereas the barge was kept fixed. In this way the gap remained constant during the tests. Numerical modeling has been undertaken using WAMIT and an in-house time-domain Rankine Panel Method (TDRPM). Response amplitude operators in terms of movements and wave amplitude in the gap obtained from seakeeping test and numerical models are documented in the paper, illustrating the limitation of the numerical codes regarding the modeling of this hydrodynamic problem. Numerical results indicate a resonant behavior of the waves in the gap for a range of frequencies, with amplitudes much higher than those observed during the tests. Due to the small distances considered in the experiments, these resonant waves are related to longitudinal wave modes in the gap. In order to overcome this problem, a procedure for introducing an external damping factor that attenuates the wave amplitude along the gap in the time-domain RPM is evaluated based on the experimental data.Copyright
ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering | 2015
Rafael A. Watai; Felipe Ruggeri; Alexandre N. Simos
This paper presents a time domain boundary elements method that accounts for relative displacements between two bodies subjected to incoming waves. The numerical method solves the boundary value problem together with a re-meshing scheme that defines new free surface panel meshes as the bodies displace from their original positions and a higher order interpolation algorithm used to determine the wave elevation and the velocity potential distribution on new free surface collocation points. Numerical solutions of exciting forces and wave elevations are compared to data obtained in a fundamental experimental text carried out with two identical circular section cylinders, in which one was attached to a load cell and the other was forced to move horizontally with a large amplitude oscillatory motion under different velocities. The comparison of numerical and experimental result presents a good agreement.Copyright
ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering | 2015
Gustavo O. Silva; Eduardo A. Tannuri; Felipe Ruggeri
Real-Time Ship Maneuvering Simulation Models is becoming more common and necessary in some feasibility analysis of ports and horizontal design. Due to the complexity of the hydrodynamic effects, a fairly realistic modeling is difficult to obtain, so that this type of simulation becomes limited in some cases. Large ships face difficulties to access ports once the shallow water and bank effects become significant. Since these factors are essential in some maneuverability studies, they must be modeled to Real-Time Simulations. In order to increase the application range of this kind of simulation, this paper presents simplified models to estimate additional hydrodynamic forces related to ship-to-ship and ship-to-bank interactions. Based on some physical input data which can be easily obtained during a Real-Time simulation, such as vessel speed and relative distances between a ship and another solid body, applying a set of measured points from the vessel to check the respective environment geometric shapes, identifying the bank conditions and other nearby vessels at a given instant. Thus, we are able to determine a realistic hydrodynamic effect. Due to the difficulty to create an accurate model, the prediction of the hydrodynamic forces was obtained from experimentally validated numerical methods such as the Boundary Elements Method (BEM), using the Rankine Panel Method. This validation consists in a comparative study among other works in this area to ensure a reliable response. The model calibration was performed using dimensionless coefficients and the BEM results are applied to the Real-Time simulation for a vessel type studied. In this study, a modeling of ship-to-ship will be presented modeled to interact in a Real-Time simulator, as a way to improve the real-time simulation and it will show that this method provides more realistic results to studies related to ship-to-ship interaction.Copyright
ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering | 2015
Pasquale Dinoi; Rafael A. Watai; Felipe Ruggeri; Jesus Gómez-Goñi; Alexandre N. Simos
In the last years hydrodynamic interaction between two vessels in side-by-side configuration is one of the hot issues in offshore floating body dynamics. The paper investigates the hydrodynamical aspects of a floating two body system. The topic is geared towards analysing the influence of the vessel’s draft in side-by-side configuration and in head sea condition. The need to solve this problem arises when one wants to study the hydrodynamic variation for the various stages of a offloading process with a defined operational gap. The system is composed of a barge and a prismatic geosim with a fixed gap value and with two barge’s draft values. Regular wave tests have been performed in the model basin of CEHINAV-Technical University of Madrid (UPM). The motion for the geosim was restricted to the surge, heave and pitch motions (just motions on the vertical plane), whereas the barge was kept fixed. The costant gap value is guaranteed during the tests. A numerical model has been created with WAMIT and with an in-house time-domain Rankine Panel Method (TDRPM). In each case the numerical and experimental response amplitude operators (RAOs) are obtained and compared, researching the limitation of the numerical codes for the gap flow modeling. In the past the gap effects on the numerical results have been studied varying the gap value finding resonant behavior in terms of motion and wave amplitude RAOs. Now the draft value contribution on the hydrodynamic effects is investigated. Also in this case the numerical results indicate a resonant behavior in determined frequencies in motion as well as in wave in the gap, that is not found in the tests. In order to overcome this problem, a procedure for introducing an external damping factor that attenuates the wave amplitude along the gap in the time-domain RPM is evaluated based on the experimental data.Copyright
ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering | 2014
Edgard Borges Malta; Felipe Ruggeri; Pedro Cardozo de Mello; Eduardo M. Vilameá; Allan C. de Oliveira; Kazuo Nishimoto
The recent discoveries and development of the Pre-salt reservoir in Brazilian coast require a new logistical model for crew transportation and transhipment to the drilling and oil rigs due to the large distance from coast, harsh environment conditions and large amount of workers to be transported against the actual model adopted considering only transportation by helicopters in order to reduce overall costs. The adoption of a logistic model with maritime transportation in these scenarios could provide several advantages, however there are several challenges from the technical point of view in transhipment between ship-shaped vessels, that could represent a great limitation in terms of operational window. Previous works showed the feasibility of monocolumn platforms with an internal moonpool as a Logistic HUB [1], allowing the boat docking in sheltered conditions. This work shows an overview of the model testing of a semi-submersible with an internal dock and the comparison of the free-surface elevation and RAOs (Response Amplitude Operators) between experimental results and potential flow computations. The tests were performed for 5 headings considering 10 regular, 5 irregular and 1 transient waves under a single draft and 5 different devices to reduce wave energy in the interior region.Copyright
Applied Ocean Research | 2015
Rafael A. Watai; Pasquale Dinoi; Felipe Ruggeri; Antonio Souto-Iglesias; Alexandre N. Simos
Marine Systems & Ocean Technology | 2015
Felipe Ruggeri; Rafael A. Watai; Pedro Cardozo de Mello; Claudio M. P. Sampaio; Alexandre N. Simos; Daniel Fonseca de Carvalho e Silva