Study on 2nd-Order Wave Loads With Forward Speed Through Aranha\u2019s Formula and Neumann-Kelvin Linearization

2021 ◽  
Author(s):  
Zhitian Xie ◽  
Jeffrey Falzarano
Keyword(s):  
Wave Loads ◽  
Forward Speed

Experimental and Numerical Investigation of the Wave-Induced Loads on a Deep-V Catamaran in Regular Waves

2013 ◽  
Author(s):  
Musa B. Bashir ◽  
Longbin Tao ◽  
Mehmet Atlar ◽  
Robert S. Dow
Keyword(s):  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
Proper Understanding ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Numerical Predictions ◽  
New Research ◽  
Wave Induced

This paper presents the results of towing tank tests carried out to predict the wave loads in regular wave conditions on a Deep-V hull form catamaran model. The experiments were carried out at the Newcastle University towing tank using a segmented model of the university’s new research vessel, “The Princess Royal”. The vessel is a twin hull with a Deep-V shape cross-section. The model, divided into two parts at the cross-deck level, was fitted with a 5-axis load cell at the position of the vessel’s centre of gravity in order to measure the motions response and wave loads due to the encountered waves. The longitudinal, side and vertical forces, along with the prying and yaw splitting moments were measured. The results obtained were further compared with those from numerical predictions carried out using a 3D panel method code based on potential flow theory that uses Green’s Function with the forward speed correction in the frequency domain. The results highlight reasonable correlations between the measurements and the predictions as well as the need for a proper understanding of the response of the multihull vessels to the wave-induced loads due to the non-linearity that have been observed in the experimental measurements of wave loads.

A Study of Dynamic Responses and Wave Loads on Ships by 3-D Green Function Method

2006 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Md. Kamruzzaman
Keyword(s):  
Green Function ◽  
Design Procedure ◽  
Ship Design ◽  
Dynamic Responses ◽  
Ship Motions ◽  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Field Problem ◽  
Dynamic Wave

The dynamic wave loads are the most significant factor for the hull design of a ship. But experimental works for the motion responses of a ship and sea loads on her are expensive and time consuming for individual ship design. Therefore, the development of theoretical and numerical methods for predicting ship motions and dynamic loads on a ship in waves is very important for rational ship design procedure. In general, though 3-D Green function techniques with forward speed need long computation time, however it should be more accurate assumption of the flow field problem on an advancing ship in waves. Nowadays the availability of much faster computer makes the 3-D Green function techniques with forward speed more familiar than before. In this paper, numerical analyses on ship motions and wave loads are presented for ships with forward speed advancing in regular waves. 3-D Green function techniques have been used to carry out the numerical computations for the radiation problem and wave loads for a moving ship. Based on the 3–D linearized potential theory, dynamic wave loads have been computed of a bulk carrier in regular waves where experimental measurements are available. The computations are carried out for various heading angles between head sea and following sea and various ranges of frequencies. The results for motions, and vertical and horizontal bending moments are presented in this paper. Computed results are compared with the experimental data. The results calculated by the present method are found in fairly good agreement with the experimental results and those calculated by the other researchers. Using developed computer code, some parametric studies are also carried out for the ship design criteria and the discussions are made.

Investigation of the Horizontal Drifting Effects on Ships With Forward Speed

2009 ◽  
Author(s):  
Sheguang Zhang ◽  
Kenneth M. Weems ◽  
Woei-Min Lin
Keyword(s):  
Horizontal Plane ◽  
Mathematical Formulation ◽  
Low Frequency ◽  
Second Order ◽  
Wave Loads ◽  
Forward Speed ◽  
Large Amplitude Motions ◽  
Domain 3 ◽  
Set Up ◽  
Control Surfaces

This paper is concerned with the horizontal drifting effects on ships moving with forward speed in waves. The ship configurations can be a single or multiple ships operating alongside one another. In close-in position (CIP) ship operations, the position of the ships often needs to be maintained relatively steady by means of Dynamic Positioning (DP) systems that incorporate thrusters or control surfaces. In developing such systems, especially those using wave feed-forward (WFF) control algorithms, the mean or low frequency drift force and moment in the horizontal plane are required to set up the control loop. The present study uses the Large Amplitude Motions Program (LAMP), a time domain, 3-D panel code for the prediction of motions and wave loads for a ship or ships in waves, to calculate the drifting forces in the horizontal plane for ships moving with or without forward speed. Since the drifting effects are second order in association with the incident wave amplitude, the formulation in LAMP has been expanded to account for the additional second order terms. This paper presents the mathematical formulation — including the second order drifting effects, its numerical implementation in LAMP, and the results from several validation cases — for a single body with or without forward speed. The analysis of the horizontal drifting effects on two-ship configurations with or without a DP system will be conducted in a future study.

Study on 2nd-Order Wave Loads With Forward Speed Through Aranha’s Formula and Neumann-Kelvin Linearization

2020 ◽  
Author(s):  
Zhitian Xie ◽  
Jeffery Falzarano
Keyword(s):  
Current Velocity ◽  
Near Field ◽  
Field Method ◽  
Wave Loads ◽  
Forward Speed ◽  
Floating Bodies ◽  
Floating Structure ◽  
Sum Frequency ◽  
Wave Drift Damping ◽  
The Mean

Abstract The 2nd-order wave loads consist of difference frequency, sum frequency components and a steady drift component that is also called the mean drift load. The first two components are usually not of interest, because of their small amplitudes compared with the 1st-order wave loads. The remaining mean drift load should be taken into consideration due to its steady effect on floating bodies. In the previous research, the full derivation and expression of the 2nd-order wave loads applied to a floating structure was presented. Moreover, numerically estimated quadratic transfer function was also illustrated with both off-diagonal elements and diagonal elements called the mean drift coefficients. Most research topics in this scenario consider the wave only case. In this paper, the mean drift wave loads applied to a floating structure with forward speed or current velocity has been numerically estimated through Aranha’s formula, a far field method and Neumann-Kelvin linearization, a near field method. Therefore, the effect of the floating structure’s forward speed or current velocity on the 2nd-order mean drift loads that is also called the wave drift damping has been discussed through these two methods. This work will provide a meaningful reference and numerical basis for the ongoing projects of the floating structure’s seakeeping and maneuvering problems.

scholarly journals Wave loads on a Semi-Submerged Catamaran (SSC) with forward speed

1990 ◽  
Vol 1990 (168) ◽  
pp. 159-170 ◽  
Author(s):  
Masanori Kobayashi ◽  
Kiyoshi Shimada ◽  
Katsuyoshi Nishimura
Keyword(s):  
Wave Loads ◽  
Forward Speed

Non-Linear Wave Loads Acting on Obliquely Slowly Advancing Platform

2009 ◽  
Author(s):  
Yasunori Nihei ◽  
Sota Sugimoto ◽  
Takashi Tsubogo ◽  
Weiguang Bao ◽  
Takeshi Kinoshita
Keyword(s):  
Boundary Value Problems ◽  
Potential Theory ◽  
Boundary Value ◽  
The Body ◽  
Linear Wave ◽  
Wave Loads ◽  
Forward Speed ◽  
Wave Drift ◽  
Non Linear ◽  
Drift Force

It is necessary to evaluate wave drift force for ships advancing obliquely. There are some approaches, for instance the strip method, solving the Navier-Stokes equation directly in the fluid domain (CFD), potential theory and so on. In the present study, the non-linear wave loads acting on the ship with constant oblique forward speed is considered based on the potential theory. Consistent perturbation expansion based on two parameters, i.e. the incident wave slope and the ratio of the forward speed compared to the phase velocity of the waves, is performed on a moving frame (body-fixed) coordinate system to simplify the problem. So obtained boundary value problems for each order of potentials is solved by means of the hybrid method. The fluid domain is divided into two regions by an artificial circular cylinder surrounding the body. The potential in the inner region is expressed by an integral over the boundary surface with a Rankin source as its Green function while it is expressed in the eigen function expansion for the outer region. Consequently, the boundary value problems can be solved efficiently. In the present paper, the authors will discuss the effects of the obliquely advancing on the wave drift force in a diffraction wave field up to the order proportional to the advancing speed. An ellipsoid model is used in the calculation and the wave drift force is evaluated for various Froude number.

Improving the Panel-Free Method for the Prediction of Ship Motions and Wave Induced Loads

2017 ◽  
Author(s):  
Wei Qiu ◽  
Heather Peng ◽  
Junshi Wang ◽  
Shahriar Nizam
Keyword(s):  
Simple Algorithm ◽  
Design Stage ◽  
Ship Motions ◽  
Wave Loads ◽  
Forward Speed ◽  
Early Design Stage ◽  
B Splines ◽  
Frequency Domain Methods ◽  
Nurbs Surfaces ◽  
Wave Induced

Frequency-domain methods are proven efficient and reliable, especially for zero forward speed, in early design stage for the prediction of ship motions and wave-induced wave loads. There are still challenges for ships with forward-speed due to the inaccuracy in the computation of m-terms. In this paper, the panel-free method is further improved to predict motions and wave-induced loads on real ships with forward speeds. A simple algorithm has been developed to re-arrange the control points for Non-Uniform Rational B-Splines (NURBS) surfaces. This method led to reliable and accurate m-term computations and therefore improved ship motion and load predictions. Validation studies have been carried out for a hydroelastic model of a frigate. Computed motions and loads were compared with experimental data.

scholarly journals WAVE-INDUCED LOADS ON CROSS-DECK OF A WAVE-PIERCING TRIMARAN WITH DIFFERENT HULL FORMS OF OUTRIGGERS

Transport ◽  
2019 ◽  
Vol 34 (5) ◽  
pp. 559-568
Author(s):  
Abolfath Askarian Khoob ◽  
Mohammad Javad Ketabdari
Keyword(s):  
Potential Flow ◽  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
High Speeds ◽  
Complex Structural ◽  
Hull Forms ◽  
Wave Induced ◽  
Study Offer

Trimaran has unique hull form with a rapidly growth in recent years due to its application as a mode of transports and naval vessels. Designing trimaran faces many technical challenges because of its complex structural outlines and high-speeds operation. This article investigates the influence of side hulls configuration (symmetric, inboard and outboard types) for wave loads on cross-deck of a trimaran ship when advancing at sea in regular waves. The computation of these hydrodynamic forces is carried out using MAESTRO-Wave 3D panel method code. This code is based on potential flow theory that uses Green’s function with the forward speed correction in the frequency domain. The results demonstrate that the outboard side hull form has the best performance on wave-induced load among three kinds of side hull forms. Furthermore, the results of this study offer more information for selecting the side hull form of the trimaran.

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