A hybrid RANSE – strip theory method for prediction of ship motions

Bonfiglio, Luca; Vernengo, Giuliano; Brizzolara, S; Bruzzone, Dario

doi:10.1201/b21890-35

Cited by 6 publications

(7 citation statements)

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“…However, since multiple coefficients have to be estimated, we chose to apply Fourier analysis. A similar approach was followed in [25,26,28,52]. The coefficients of the Fourier series of the force F z (t) (Equation ( 26)) acting on the heaving WEC can be used to calculate the hydrodynamic coefficients.…”

Section: Determination Of Hydrodynamic Coefficients Using Dualsphysicsmentioning

confidence: 99%

Influence of the Drag Force on the Average Absorbed Power of Heaving Wave Energy Converters Using Smoothed Particle Hydrodynamics

Quartier

Ropero-Giralda

Domínguez

et al. 2021

Water

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In this paper, we investigated how the added mass, the hydrodynamic damping and the drag coefficient of a Wave Energy Converter (WEC) can be calculated using DualSPHysics. DualSPHysics is a software application that applies the Smoothed Particle Hydrodynamics (SPH) method, a Lagrangian meshless method used in a growing range of applications within the field of Computational Fluid Dynamics (CFD). Furthermore, the effect of the drag force on the WEC’s motion and average absorbed power is analyzed. Particularly under controlled conditions and in the resonance region, the drag force becomes significant and can greatly reduce the average absorbed power of a heaving point absorber. Once the drag coefficient has been determined, it is used in a modified equation of motion in the frequency domain, taking into account the effect of the drag force. Three different methods were compared for the calculation of the average absorbed power: linear potential flow theory, linear potential flow theory modified to take the drag force into account and DualSPHysics. This comparison showed the considerable effect of the drag force in the resonance region. Calculations of the drag coefficient were carried out for three point absorber WECs: one spherical WEC and two cylindrical WECs. Simulations in regular waves were performed for one cylindrical WEC with two different power take-off (PTO) systems: a linear damping and a Coulomb damping PTO system. The Coulomb damping PTO system was added in the numerical coupling between DualSPHysics and Project Chrono. Furthermore, we considered the optimal PTO system damping coefficient taking the effect of the drag force into account.

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Section: Determination Of Hydrodynamic Coefficients Using Dualsphysicsmentioning

confidence: 99%

Influence of the Drag Force on the Average Absorbed Power of Heaving Wave Energy Converters Using Smoothed Particle Hydrodynamics

Quartier

Ropero-Giralda

Domínguez

et al. 2021

Water

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“…6, transfer functions of heave and pitch motions, TF 3 and TF 5 can be obtained by using Eqs. (20) and 21:…”

Section: Calculation Of Hydrodynamic Coefficients and Ship Motionsmentioning

confidence: 99%

“…The results of hydrodynamic coefficients showed good agreement in comparison with experimental results. Bonfiglio et al [20] calculated the radiation terms of 2-D sections of the ship and obtained the 3-D radiation terms by applying the strip theory method. They separated the radiation and excitation terms and predicted transfer functions by solving linear vertical motion equations.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on hydrodynamic coefficients and longitudinal motions of trimaran in head seas for various wave slopes

Zhang

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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In this study, numerical simulations for the prediction of hydrodynamic coefficients and longitudinal motions of a trimaran vehicle in regular head waves with varying wave slopes are presented for a wide range of wave conditions. Wave excitation and radiation terms in 2DOF equations of longitudinal motions of the ship in regular head seas are obtained, using an unsteady Reynolds averaged Navier-Stokes (URANS) solver based on finite volume method. A trimaran hull form is used for the calculations at a relative high Froude number of 0.628. Numerical simulations are performed for eight different regular wave conditions with varying wave slopes. Firstly, the verification study is performed to determine an optimal mesh system and time step for CFD simulations. Secondly, numerical simulations are carried out to predict hydrodynamic coefficients and longitudinal motion responses and the results are compared with those obtained from the fully URANS approach and experiments. Finally, the relationship between the hydrodynamic coefficients and longitudinal motions are investigated with varying wave slopes. Systematic studies of the numerical simulations demonstrate that the numerical results have a reasonable agreement with the experimental data. The nonlinearities effects of wave slopes on the hydrodynamic coefficients and vertical motion of the trimaran are studied and analyzed taking the viscous effect and free surface nonlinearities into consideration.

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“…Fully viscous models such as URANS have been mostly applied to the solution of problems that have a large economical impact (see [27,29,30,35]) or to unconventional geometries where conventional potential flow theories fail (see [31,32,36,37]). A drawback is that URANS depends on empirical modelling of turbulence.…”

Section: Introductionmentioning

confidence: 99%

Influence of Viscosity and Non-Linearities in Predicting Motions of a Wind Energy Offshore Platform in Regular Waves

Ferrandis

Bonfiglio

Rodríguez

et al. 2020

Journal of Offshore Mechanics and Arctic Engineering

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Motion predictions of floating bodies in extreme waves represent a challenging problem in naval hydrodynamics. The solution of the seakeeping problem involves the study of complex non-linear wave-body interactions that require large computational costs. For this reason, over the years, many seakeeping models have been formulated in order to predict ship motions using simplified flow theories, usually based on potential flow theories. Neglecting viscous effects in the wave-induced forces might largely underestimate the energy dissipated by the system. This problem is particularly relevant for unconventional floating bodies at resonance. In these operating conditions, the linear assumption is no longer valid, and conventional boundary element methods, based on potential flow, might predict unrealistic large responses if not corrected with empirical viscous damping coefficients. The application considered in this study is an offshore platform to be operated in a wind farm requiring operability even in extreme meteorological conditions. In this paper, we compare heave and pitch response amplitude operators predicted for an offshore platform using three different seakeeping models of increasing complexity, namely, a frequency-domain boundary element method (BEM), a partly nonlinear time domain BEM, and a non-linear viscous model based on the solution of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations. Results are critically compared in terms of accuracy, applicability, and computational costs.

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A hybrid RANSE – strip theory method for prediction of ship motions

Cited by 6 publications

References 0 publications

Influence of the Drag Force on the Average Absorbed Power of Heaving Wave Energy Converters Using Smoothed Particle Hydrodynamics

Influence of the Drag Force on the Average Absorbed Power of Heaving Wave Energy Converters Using Smoothed Particle Hydrodynamics

Numerical study on hydrodynamic coefficients and longitudinal motions of trimaran in head seas for various wave slopes

Influence of Viscosity and Non-Linearities in Predicting Motions of a Wind Energy Offshore Platform in Regular Waves

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