Vallam Sundar

Bio: Vallam Sundar is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Wind wave & Shore. The author has an hindex of 24, co-authored 195 publications receiving 1778 citations. Previous affiliations of Vallam Sundar include Indian Institutes of Technology.

Artificial Reefs: A Review

Abstract: A comprehensive literature review on the material characteristics, design of size and shape, application and management of artificial reef has been carried out. Multipurpose Artificial Surfing Reefs (MPASR) are increasingly being adopted for coastal protection because of several advantages associated with them such as coastal protection by reducing the wave energy, recreation of beaches (surfing, fishing, and diving), habitat for marine organisms and increase in socioeconomic prosperity. The most important characteristic is that they are soft barriers. It is concluded that although artificial reefs do have the ability to fulfill many objectives, for which they are meant, their success will depend mainly on the quality of planning and management prior to their implementation.

Hydrodynamic Characteristics of Curved-Front Seawall Models Compared with Vertical Seawall under Regular Waves

Abstract: Seawalls remain one of the most widely adopted coastal-protection measure. The seawalls should be stable to ensure safety and optimally use the coastal space with a minimum or no waves overtopping but still keeping the crest elevation low. This may possibly be achieved by reshaping the front 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 as the background, an experimental study measuring run-up and overtopping of three different types of curved-front face seawall models, as well as the dynamic pressures exerted on each of them, was carried out. The measured parameters for the three types of 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 regular waves. The details of the test facility, models, experimental program, results, and analysis are presented and discussed...

Runup and Inundation along the Indian Peninsula, Including the Andaman Islands, due to Great Indian Ocean Tsunami

Abstract: The December 2004 Sumatra earthquake triggered massive tsunami waves in the Indian Ocean and the Bay of Bengal. The tsunami waves traveled primarily in the east-west direction and caused major damage along the coasts of southern India, Sri Lanka, Thailand, and Indonesia. It has proved to be the most disastrous tsunami in recorded history, and scientists and engineers around the world set out to record signatures of the tsunami from which the characteristics of the tsunami waves at the time of landfall could be deciphered. Such information is extremely useful in validating mathematical models for understanding the characteristics of tsunamis and their effects along the coast. The writers conducted surveys along the east and west coasts of peninsular India—focusing on the states of Tamil Nadu and Kerala and around Andaman and Nicobar Islands, where the devastation caused by the tsunami was unparalleled. The analysis of data gathered during the post-sunami survey focused on consolidating the primary paramete...

A new family of generalized distributions

Abstract: 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...

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

Abstract: 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.

Random seas and design of maritime structures

Abstract: 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.

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

Abstract: 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.