Nonlinear Oscillations: Exact Solutions and their Approximations

Kumaraswamy [Generalized probability density-function for double-bounded random-processes, J. Hydrol. 462 (1980), pp. 79–88] introduced a distribution for double-bounded random processes with hydrological applications. For the first time, based on this distribution, we describe a new family of generalized distributions (denoted with the prefix ‘Kw’) to extend the normal, Weibull, gamma, Gumbel, inverse Gaussian distributions, among several well-known distributions. Some special distributions in the new family such as the Kw-normal, Kw-Weibull, Kw-gamma, Kw-Gumbel and Kw-inverse Gaussian distribution are discussed. We express the ordinary moments of any Kw generalized distribution as linear functions of probability weighted moments (PWMs) of the parent distribution. We also obtain the ordinary moments of order statistics as functions of PWMs of the baseline distribution. We use the method of maximum likelihood to fit the distributions in the new class and illustrate the potentiality of the new model with a...

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A new family of generalized distributions

Wind speeds over the world’s oceans have increased over the past two decades, as have wave heights. Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

https://researchbank.swinburne.edu.au/file/bca43746-6f16-4ad2-a4b7-27f8d8d60fed/1/PDF (Published version).pdf

Global trends in wind speed and wave height over the past 25 years

Evolution of Design Method Against Random Waves Statistical Properties and Spectral of Sea Waves Transformation and Deformation of Random Sea Waves Design of Breakwaters Design of Coastal Dikes and Seawalls Probabilistic Design of Harbor Facilities Harbor Tranquility and Vessel Mooring Hydraulic Model Tests with Random Waves Theoretical Description of Random Sea Waves Statistical Theory of Irregular Waves Techniques of Random Wave Analysis 2D Computation of Wave Transformation with Random Breaking and Nearshore Currents Statistical Analysis of Extreme Waves Prediction and Control of Beach Deformation Processes.

Random seas and design of maritime structures

The interaction of waves with obstacles is an everyday phenomenon in science and engineering, arising for example in acoustics, electromagnetism, seismology and hydrodynamics. The mathematical theory and technology needed to understand the phenomenon is known as multiple scattering, and this book is the first devoted to the subject. The author covers a variety of techniques, describing first the single-obstacle methods and then extending them to the multiple-obstacle case. A key ingredient in many of these extensions is an appropriate addition theorem: a coherent, thorough exposition of these theorems is given, and computational and numerical issues around them are explored. The application of these methods to different types of problems is also explained; in particular, sound waves, electromagnetic radiation, waves in solids and water waves. A comprehensive bibliography of some 1400 items rounds off the book, which will be an essential reference on the topic for applied mathematicians, physicists and engineers.

Multiple Scattering: Interaction of Time-Harmonic Waves with N Obstacles

The sloshing phenomenon of liquid in a partially filled tank mounted rigidly within a barge exposed to regular wave field has been considered for numerical investigation. This paper details the numerical scheme developed in time domain to study the interaction of wave induced barge motion with sloshing oscillations in a partially filled container. The sloshing time history results obtained from the numerical scheme adopted are validated with experimental measurements of Nasar et al. (2008) The harmonics present in the sloshing oscillation for the liquid fill levels (25%, 50% and 75%) have been analyzed.

Numerical modeling of nonlinear sloshing of liquid in a container coupled with barge subjected to regular excitation

Seawalls are the most widely adopted coastal protection measure. The design of an efficient seawall should be such that overtopping is minimized even during coastal flooding and extreme events by maintaining its crest elevation lower. This may possibly be achieved by reshaping the front shape of the structure in such a way that it offers maximum resistance to the flow or enhances the dissipation of incident wave energy. With this background, an experimental study on the measurement of run-up and dynamic pressures over three different types of curved front face seawall models along with a vertical seawall was carried out. The measured parameters for the three types of curved seawalls are compared with that for a vertical seawall. All the tests were carried out with the models rigidly fixed over a bed slope of 1 in 30 in a wave flume and subjected to the action of Cnoidal waves. The dynamic pressure distributions measured along the surface and the run-up over the models are reported in a dimensionless form as a function of relative water depth and ursell parameter. The details of the test facility, models, experimental program, results and analysis are presented and discussed in this paper.

http://nopr.niscair.res.in/bitstream/123456789/10806/1/IJMS%2039%284%29%20579-588.pdf

Dynamic pressure and run-up on curved seawalls compared with vertical wall under cnoidal waves

Wind climate for Madras Harbour, India

Simulation of nonlinear free surface dispersive shallow water waves

Extreme coastal events require careful prediction of wave forces. Recent tsunamis have resulted in extensive damage of coastal structures. Such scenarios are the result of the action of long waves on structures. In this paper, the efficiency of vegetation as a buffer system in attenuating the incident ocean waves was studied through a well controlled experimental program. The study focused on the measurement of forces resulting from cnoidal waves on a model building mounted over a slope in the presence and absence of vegetation. The vegetative parameters, along with the width of the green belt, its position from the reference line, the diameter of the individual stems as well as the spacing between them, and their rigidity are varied so as to obtain a holistic view of the wave-vegetation interaction problem. The effect of vegetation on variations of dimensional forces with a Keulegan-Carpenter number (KC) was discussed in this paper. It has been shown that when vegetal patches are present in front of structure, the forces could be limited to within F*≤1, by a percentile of 92%, 90%, 55%, and 96%, respectively for gap ratios of 0.0, 0.5, 1.0, and 1.5. The force is at its maximum for the gap ratio of 1.0 and beyond which the forces start to diminish.

Vallam Sundar

Papers

Numerical modeling of nonlinear sloshing of liquid in a container coupled with barge subjected to regular excitation

Dynamic pressure and run-up on curved seawalls compared with vertical wall under cnoidal waves

Wind climate for Madras Harbour, India

Simulation of nonlinear free surface dispersive shallow water waves

The effects of flexible vegetation on forces with a Keulegan-Carpenter number in relation to structures due to long waves