On the development of a higher order time-domain Rankine panel method for linear and weakly non-linear seakeeping computations

2018 ◽  
Vol 40 (2) ◽  
Author(s):  
Felipe Ruggeri ◽  
Rafael A. Watai ◽  
Claudio M. P. Sampaio ◽  
Alexandre N. Simos
Keyword(s):  
Time Domain ◽  
Higher Order ◽  
Panel Method ◽  
Rankine Panel Method ◽  
Non Linear

A 3D Higher Order Time Domain Rankine Panel Method for Wave-Current Interaction

2016 ◽  
Author(s):  
Felipe Ruggeri ◽  
Rafael A. Watai ◽  
Alexandre N. Simos
Keyword(s):  
Time Domain ◽  
Higher Order ◽  
Second Order ◽  
Panel Method ◽  
Order Effects ◽  
Rankine Panel Method ◽  
Wave Drift Damping ◽  
Current Interaction ◽  
Order Quantities ◽  
The University

The wave-current effects are very important in several offshore applications, for instance, the wave-drift-damping of a Turret moored FPSO. This papers presents the incorporation of current effects in the higher order time domain Rankine Panel Method on development in the Numerical Offshore Tank (TPN) at the University of São Paulo (USP) already introduced in [1]. The method is based on a perturbation theory to study first and second order effects, considering the geometry described using NURBS (Non Uniform Rational Basis Spline) and the potential function, free surface elevation, pressure etc by B-splines of arbitrary degree. The study is performed for a simplified geometry (sphere) and the results regarding a fixed hemisphere compared to other numerical methods considering both first and second order quantities are presented.

Ship Seakeeping Through the t = 1/4 Critical Frequency

1998 ◽  
Vol 42 (02) ◽  
pp. 113-119
Author(s):  
D. C. Kring
Keyword(s):  
Numerical Analysis ◽  
Time Domain ◽  
Critical Frequency ◽  
Three Dimensional ◽  
Panel Method ◽  
Gravitational Acceleration ◽  
Forward Speed ◽  
Rankine Panel Method ◽  
Physical Experiments

This study demonstrates that a bounded, physically relevant solution does exist at the so-called T = Uω/g = 1/4 resonance in the linear seakeeping problem for a realistic ship with forward speed, U, frequency of encounter, ω, and gravitational acceleration, g. The solution of the seakeeping problem by a linear, three dimensional, time-domain Rankine panel method, validated through numerical analysis, testing, and comparison to physical experiments, supports this claim. The solution can also be obtained with equal validity through frequencies both above and below the critical frequency.

A Higher Order Time Domain Rankine Panel Method for Linear and Weakly Non-Linear Computation

2015 ◽  
Author(s):  
Felipe Ruggeri ◽  
Rafael A. Watai ◽  
Alexandre N. Simos
Keyword(s):  
Time Domain ◽  
Domain Boundary ◽  
Higher Order ◽  
Floating Body ◽  
Wave Runup ◽  
Floating Bodies ◽  
B Splines ◽  
Non Linear ◽  
Boundary Elements Method ◽  
Linear Effects

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.

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