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

Wave forces and moments on an intake well

The sloshing pressures on the side wall and on the top cover plate of a tank partially filled with liquid and rigidly mounted on a barge in irregular waves are investigated through physical model tests. The barge was allowed to oscillate freely in the combined degrees of excitation, i.e. sway, heave, and roll. Four liquid fill levels with aspect ratios hs/l (where hs is the static liquid depth and l is the tank length) of 0.163, 0.325, 0.488, and 0.585 are considered for the present study. The effect of peak wave excitation frequencies on the pressure variation is studied in detail, the results of which are herein reported. It is observed that the impact pressure on the top panel of the tank is about 1.6 times the pressure observed on the side wall.

Wave-induced sloshing pressure in a liquid tank under irregular waves

The submerged semicircular breakwater (SBW) is mainly adopted to prevent beach erosion and to reduce the incident wave energy on its leeside, if it is used in front of a vertical breakwater. In addition, it facilitates the premature wave breaking, which in turn causes the reduction in wave energy. The dynamic pressures and forces exerted on the submerged SBW with 7%, 11 %, and 17% of the exposed surface area with perforations on its seaside due to regular waves were measured. The hydrodynamic characteristics such as variations in the dimensionless pressures and forces, reflection and transmission coefficients on the semicircular caisson as a function of scattering parameter for three different water depths are presented and an optimum depth of submergence is arrived. The results on the above stated variables for seaside perforated SBWs are compared with the results of an impermeable SBW to study the effect of perforations.

Regular Wave Measurements on a Submerged Semicircular Breakwater

Wave characteristics off the south east coast of India

The shoreline erosion is a major problem that persist world wide and seawall still remain as one of the most widely adopted coastal protection structure. 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 as low as possible. This can be obtained with curved front face sea walls. Two such curved configurations have been chosen for the study. The experimental investigation on dynamic pressure variation along the surface of the seawall models placed over a bed slope of 1 in 30 and subjected to the action of random waves following the PM spectrum were conducted. The results on the variations of dynamic pressures on the seaward face of both the models along the relative depth are compared and discussed.

Vallam Sundar

Papers

Wave forces and moments on an intake well

Wave-induced sloshing pressure in a liquid tank under irregular waves

Regular Wave Measurements on a Submerged Semicircular Breakwater

Wave characteristics off the south east coast of India

Dynamic pressures on curved front seawall models under random waves