scholarly journals WAVE LOADS ON A NAVIGATION LOCK SLIDING GATE: NON-LINEAR EFFECTS

2020 ◽  
pp. 8
Author(s):  
Luca Cavallaro ◽  
Claudio Iuppa ◽  
Rosaria Ester Musumeci ◽  
Pietro Scandura ◽  
Enrico Foti
Keyword(s):  
Analytical Model ◽  
Cfd Simulation ◽  
Analytical Models ◽  
Wave Number ◽  
Linear Wave ◽  
Vertical Force ◽  
Wave Loads ◽  
Vertical Load ◽  
Non Linear ◽  
Navigation Lock

The wave loads on a navigation lock gate provided with an opening in the ballast tank are analyzed using a mathematical model based on the linear wave theory and the numerical integration of the Navier-Stokes Equation. The analysis focuses on the evaluation of the non-linear effect influence on the vertical load on the gate. It is shown that the numerical and analytical models agree on the identification of the value of the wave number at which the maximum value of the dimensionless vertical force on the gate is detected. However the analytical model overestimates the peak value of the vertical load with respect to the CFD simulation. To fill this gap, in this paper an easy to use procedure is developed which allows to correct the results of the analytical model.

scholarly journals Wave-induced loads on a lock gate provided with an opening through the ballast tank

2020 ◽  
Vol 6 (4) ◽  
pp. 415-425
Author(s):  
Luca Cavallaro ◽  
Claudio Iuppa ◽  
Pietro Scandura ◽  
Enrico Foti
Keyword(s):  
Mathematical Model ◽  
Wave Theory ◽  
Maximum Load ◽  
Wave Number ◽  
Linear Wave ◽  
Vertical Force ◽  
Wave Loads ◽  
Wave Load ◽  
Ballast Tank ◽  
Lock Gate

AbstractThe wave loads on a navigation lock gate provided with an opening in the ballast tank are analyzed using a mathematical model based on the linear wave theory. The analysis focuses on the influence of the wave number and the geometrical characteristics of the structure on the applied load. It is shown that the maximum value of the vertical force mainly depends on the height of the ballast tank and on the width of the opening. The wave number for which the maximum load occurs significantly depends on the geometric characteristics of the structure except for the water depth above the ballast tank which has a negligible effect. An increase in the height of the ballast tank causes an increase in the wave load while an increase in the width of the opening causes a decrease in the wave load. Based on the results of the mathematical model an easy to use regression model has been developed which can be employed to evaluate the wave load.

Non-linear wave-number interaction in near-critical two-dimensional flows

1971 ◽  
Vol 49 (4) ◽  
pp. 705-744 ◽  
Author(s):  
R. C. Diprima ◽  
W. Eckhaus ◽  
L. A. Segel
Keyword(s):  
Travelling Waves ◽  
Fundamental Equation ◽  
Linear Partial Differential Equation ◽  
Original System ◽  
Basic Flow ◽  
Linear Stability Theory ◽  
Wave Number ◽  
Linear Wave ◽  
Special Cases ◽  
Non Linear

This paper deals with a system of equations which includes as special cases the equations governing such hydrodynamic stability problems as the Taylor problem, the Bénard problem, and the stability of plane parallel flow. A non-linear analysis is made of disturbances to a basic flow. The basic flow depends on a single co-ordinate η. The disturbances that are considered are represented as a superposition of many functions each of which is periodic in a co-ordinate ξ normal to η and is independent of the third co-ordinate direction. The paper considers problems in which the disturbance energy is initially concentrated in a denumerable set of ‘most dangerous’ modes whose wave-numbers are close to the critical wave-number selected by linear stability theory. It is a major result of the analysis that this concentration persists as time passes. Because of this the problem can be reduced to the study of a single non-linear partial differential equation for a special Fourier transform of the modal amplitudes. It is a striking feature of the present work that the study of a wide class of problems reduces to the study of this single fundamental equation which does not essentially depend on the specific forms ofthe operators in the original system of governing equations. Certain general conclusions are drawn from this equation, for example for some problems there exist multi-modal steady solutions which are a combination of a number of modes with different spatial periods. (Whether any such solutions are stable remains an open question.) It is also shown in other circumstances that there are solutions (at least for some interval of time) which are non-linear travelling waves whose kinematic behaviour can be clarified by the concept of group speed.

scholarly journals Analytical Model of Wave Loads and Motion Responses for a Floating Breakwater System with Attached Dual Porous Side Walls

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Weiliang Qiao ◽  
Keh-Han Wang ◽  
Wenqi Duan ◽  
Yuqing Sun
Keyword(s):  
Analytical Model ◽  
Dynamic Responses ◽  
Body Motion ◽  
Linear Wave ◽  
Wave Loads ◽  
Vertical Side ◽  
Damping Coefficients ◽  
Floating Breakwater ◽  
Exciting Forces ◽  
Porous Walls

A set of two-dimensional analytical solutions considering the effects of diffraction and radiation are presented in this study to investigate the hydrodynamic interaction between an incident linear wave and a proposed floating breakwater system consisting of a rectangular-shaped body and two attached vertical side porous walls in an infinite fluid domain with finite water depth. The Matched Eigenfunction Expansion Method (MEEM) for multiple fluid domains is applied to derive theoretically the velocity potentials and associated unknown coefficients for wave diffraction and body motion induced radiation in each subdomain. Also, the exciting forces, as well as the added mass and damping coefficients for the floating breakwater system under the surge, heave, and pitching motions, are formulated. The displacements of breakwater motions are determined by solving the equation of motion. As a verification of the analytical model, the present solutions of the limiting cases in terms of exciting forces, moments, added masses, and damping coefficients are found to be well matched with other published numerical results. Additionally, the hydrodynamic performances and the dynamic responses in terms of Response Amplitude Operators (RAOs) of the proposed floating breakwater system are evaluated versus various dimensionless variables, such as wavelength and porous-effect parameter. The results show that the attached porous walls with selected porous properties are observed to have the advantages of reducing wave impacts on the floating breakwater system and at the same time its dynamic responses are also noticeably improved.

Non-linear wave loads and ship responses by a time-domain strip theory

1998 ◽  
Vol 11 (3) ◽  
pp. 101-123 ◽  
Author(s):  
Jinzhu Xia ◽  
Zhaohui Wang ◽  
J.Juncher Jensen
Keyword(s):  
Time Domain ◽  
Linear Wave ◽  
Wave Loads ◽  
Strip Theory ◽  
Non Linear

Fatigue Assessment for Ship Structure Acted on Non-Linear Wave Loads

2007 ◽  
Vol 353-358 ◽  
pp. 2786-2789
Author(s):  
Chao He Chen
Keyword(s):  
Fatigue Damage ◽  
Bending Moment ◽  
Linear Wave ◽  
Wave Loads ◽  
Ship Structure ◽  
Random Seas ◽  
Non Linear ◽  
Bow Flare ◽  
Short Term Prediction ◽  
The Given

Efficient methods are described here to predict the fatigue damage of ship structure due to nonlinear wave loads that are produced in random seas. Firstly the effects of the non-linear waveinduced bending moment on the fatigue damage of ship structure with very large bow flare are presented in short-term prediction by the method of spectrum analysis. Then, the fatigue damage is estimated and analyzed in the given environment of long-term.

Study on Non-Linear Numerical Method of Composite Foundation with Rigid-Flexible Piles

2013 ◽  
Vol 671-674 ◽  
pp. 133-136
Author(s):  
Shao Chong Yang ◽  
Jian Hui Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Method ◽  
Analytical Model ◽  
Composite Foundation ◽  
Vertical Load ◽  
The Finite Element Method ◽  
Soil System ◽  
Non Linear ◽  
Pile Interaction

A non-linear numerical method of composite foundation with rigid-flexible piles in the stratified soil under the vertical load was established in this paper. The analytical model of the pile-soil-pile interaction was used to imitate the pile-soil system and the finite element method was applied to simulate the cushion (the cushion cap). The corresponding calculation program was programmed. Computation results show that the method is reasonable and feasible, and can be applied to the analysis of practical composite foundation.

Full-Scale Measurements on Hull Response of a Large-Container Ship in Service

2006 ◽  
Author(s):  
Kenichiro Miyahara ◽  
Ryuju Miyake ◽  
Norikazu Abe ◽  
Atsushi Kumano ◽  
Masanobu Toyoda ◽  
...  
Keyword(s):  
High Harmonic ◽  
Bending Moment ◽  
Full Scale ◽  
Linear Wave ◽  
Container Ship ◽  
Wave Loads ◽  
Non Linear ◽  
Large Container ◽  
Probability Density Distributions

In order to investigate hull responses of post-Panamax container ships in the actual sea, full-scale measurements on hull responses of a post-Panamax container ship in service were conducted. In linear wave domain, the probability density distributions of hull responses obtained by full-scale measurements were compared with the Rayleigh distributions to check on the range of the applicability, and comparisons with the long-term distributions of the longitudinal stress obtained by full-scale measurements and the direct structural analyses based on the wave loads analyzed by using the linear 3D Rankine source method were made to verify the accuracy. In non-linear wave domain, the measured longitudinal stresses showed the asymmetry of vertical bending moment. The long-term distributions of hull responses, which have the high harmonic components, obtained by full-scale measurements were compared with the numerical results analyzed by using non-linear methods to investigate the non-linearity on hull responses of container ship.

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.

scholarly journals An Experimental Investigation of Wave Forces on a Submerged Horizontal Plate over a Simple Slope

2020 ◽  
Vol 8 (7) ◽  
pp. 507
Author(s):  
Jie Dong ◽  
Leiping Xue ◽  
Kaiyu Cheng ◽  
Jian Shi ◽  
Chi Zhang
Keyword(s):  
Wave Length ◽  
Wave Forces ◽  
Linear Wave ◽  
Intermediate Water ◽  
Vertical Force ◽  
Wave Loads ◽  
Horizontal Plate ◽  
Flat Bottom ◽  
Simple Slope ◽  
Submerged Horizontal Plate

We experimentally investigated the forces induced by monochromatic and solitary waves on a submerged horizontal plate in a wave flume. The experimental results of two-dimensional wave forces on the plate over a 1:10 simple slope and a flat bottom are presented. The effects of the uneven bottom on wave loads are discussed by comparing the results with those in a constant water depth. The measured nonlinear wave forces exhibited considerable discrepancies with the theoretical results from the linear wave theory. The wave forces on the plate induced by monochromatic waves over the simple slope in intermediate water showed no appreciable difference with the flat-bottom results. The solitary wave forces in terms of the downward vertical force and overturning moment significantly decreased in the existence of the simple slope. Furthermore, the dependency of the wave length, wave height and the submergence depth on the wave loads is also discussed.

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