scholarly journals On Numerical Treatments of the Infinite Condition in the Frequency-Domain Rankine Panel Method

2016 ◽  
Vol 24 (0) ◽  
pp. 105-127
Author(s):  
Hidetsugu Iwashita
Keyword(s):  
Frequency Domain ◽  
Panel Method ◽  
Rankine Panel Method ◽  
Numerical Treatments

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.

scholarly journals Waves’ Numerical Dispersion and Damping due to Discrete Dispersion Relation

2014 ◽  
Author(s):  
Babak Ommani ◽  
Odd M. Faltinsen
Keyword(s):  
Free Surface ◽  
Dispersion Relation ◽  
Surface Waves ◽  
Boundary Integral ◽  
Panel Method ◽  
Numerical Dispersion ◽  
Finite Difference Schemes ◽  
Rankine Panel Method ◽  
Free Surface Waves ◽  
The Waves

In linear Rankine panel method, the discrete linear dispersion relation is solved on a discrete free-surface to capture the free-surface waves generated due to wave-body interactions. Discretization introduces numerical damping and dispersion, which depend on the discretization order and the chosen methods for differentiation in time and space. The numerical properties of a linear Rankine panel method, based on a direct boundary integral formulation, for capturing two and three dimensional free-surface waves were studied. Different discretization orders and differentiation methods were considered, focusing on the linear distribution and finite difference schemes. The possible sources for numerical instabilities were addressed. A series of cases with and without forward speed was selected, and numerical investigations are presented. For the waves in three dimensions, the influence of the panels’ aspect ratio and the waves’ angle were considered. It has been shown that using the cancellation effects of different differentiation schemes the accuracy of the numerical method could be improved.

Economical Proposal for an Offshore Logistic Hub

2017 ◽  
Author(s):  
Peyman Asgari ◽  
Antonio Carlos Fernandes
Keyword(s):  
Rigid Body ◽  
Frequency Domain ◽  
Deep Water ◽  
Vertical Motion ◽  
Panel Method ◽  
Offshore Platforms ◽  
Oil Exploration ◽  
Remote Terminal ◽  
Floating Breakwater ◽  
Two Bodies

Oil exploration in the pre-salt, mainly in the SANTOS BASIN, has increased significantly and as results increasing the number of thousands of people commute to offshore platforms in Brazil is inevitable. The presence of a remote terminal, the so-called HUB, adjacent to the platforms, not only reduces the shipment costs, but also increases the speed of commuting. The present work addresses the feasibility of utilizing a ship shape hull as an alternative logistic HUB. The present work analyzes the hull as a rigid body receiving mostly transversal waves and operating as a floating breakwater in deep water with a central turret. The crew boat is a HSV, which will also be included in the investigation. As a continuation of the previous study of the author in 2015, the relative vertical motion between two bodies is analyzed in (four) different configurations and angles of incoming waves by the panel method code in frequency domain. Finally, having in mind operation limits and criterion, operation probabilities are evaluated. Four configurations are considered to be analyzed numerically on the relative vertical motion between two bodies in different Configurations and different angles of incoming waves by a panel method code for frequency domain. Finally, operation probabilities are studied according to the operation limits and criterion.

A Rankine Panel Method for Added Resistance of Ships in Waves

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Heinrich Söding ◽  
Vladimir Shigunov ◽  
Thomas E. Schellin ◽  
Ould el Moctar
Keyword(s):  
Degrees Of Freedom ◽  
Periodic Wave ◽  
Panel Method ◽  
Navier Stokes ◽  
Ship Motions ◽  
Added Resistance ◽  
Rankine Panel Method ◽  
Head Waves ◽  
Wigley Hull ◽  
The Time Domain

A new Rankine panel method and an extended Reynolds-Averaged Navier–Stokes (RANS) solver were employed to predict added resistance in head waves at different Froude numbers of a Wigley hull, a large tanker, and a modern containership. The frequency domain panel method, using Rankine sources as basic flow potentials, accounts for the interaction of the linear periodic wave-induced flow with the nonlinear steady flow caused by the ship's forward speed in calm water, including nonlinear free surface conditions and dynamic squat. Added resistance in waves is obtained by the pressure integration method. The time domain RANS solver, based on a finite volume method, is extended to solve the nonlinear equations of the rigid body six-degrees-of-freedom ship motions. The favorable comparison of the panel and RANS predictions demonstrated that the Rankine method is suitable to efficiently obtain reliable predictions of added resistance of ships in waves. Comparable model test predictions correlated less favorably, although the overall agreement was felt to be acceptable, considering the difficulties associated with the procedures to obtain accurate measurements.

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