Showing papers by "Vallam Sundar published in 2008"

Sloshing pressure variation in a barge carrying tank

Abstract: An experimental study has been carried out to measure the pressures on the walls and on the top cover plate of a tank that is partially filled with liquid and rigidly mounted in a barge. Herein, the barge has been subjected to the combined degrees of excitation, namely, sway, heave and roll. Four liquid fill levels with aspect ratio (h s /l, where h s is the static liquid depth and l is the tank length) of 0.163, 0.325 (nearly critical depth), 0.488 and 0.585 are considered for the studies. The effects of wave excitation frequencies and amplitudes on the pressure variation have been studied in detail and, the salient results are herein reported.

Hydrodynamic Characteristics of Seaside Perforated Semicircular Breakwaters due to Random Waves

Abstract: The semicircular breakwater (SBW) is a composite breakwater consisting of a semicircular caisson resting on a rubble mound. The SBW function as a barrier dissipates the incident wave energy and creates tranquility on its leeside. The dynamic pressures due to random waves exerted on seaside perforated SBWs with 7, 11, and 17% of its exposed surface area with perforations were measured. The measured pressures are compared with experimental results of SBW without perforations. In addition, the forces exerted on the caisson alone are measured. The reflection coefficient, runup characteristics, measured total forces, and dynamic pressures in a dimensionless form are presented as a function of relative water depth. The tests were conducted for surface piercing conditions. The effect of the water depth, perforations, and rubble mound height on the above stated variables are brought out, the details of which are reported in this technical note.

Reflection and transmission characteristics of partially submerged slotted wave screens

Abstract: The wave reflection and transformation characteristics of partially submerged slotted screens, consisting of horizontal wave intercepting elements, have been studied using the Green’s Identity formula. The effects of the relative depth of submergence of the wave screen on its hydrodynamic performance characteristics under the action of regular and random waves are investigated through numerical and experimental studies. The comparisons of reflection, transmission coefficients as well as the dynamic pressures exerted on the individual wave screen elements from experiments with numerical results are found to be in close agreement. The details of the numerical method, physical model, hydrodynamic testing facility, experimental setup, procedure and analysis along with the interpretation of results are presented and discussed in this paper. A screen height below the water level of 0.3d, where d is the water depth, is found to be an optimal system.

Interaction of Solitary Waves With a Group of Dual Porous Circular Cylinders

Abstract: Diffraction of solitary waves around a group of dual porous cylinders consisting of a thin and porous outer cylinder circumscribing an impermeable inner cylinder is investigated analytically based on the eigenfunction expansion method. The present formulation is an extension of the work of Zhong and Wang (2006), wherein; the interaction of solitary waves with a single concentric porous cylinder system was studied. This paper aims at investigating the influence of multiple interactions between the cylinders in a group on the hydrodynamic wave forces, wave run-up and free-surface elevation in their vicinity. Further, the study focuses on the variation of the forces on the individual cylinders within the group compared to that on isolated cylinders.Copyright © 2008 by ASME

Explicit FE Modeling of Indian Ocean Tsunami Using Unstructured Mesh

Abstract: Propagation of the Indian Ocean Tsunami has been simulated using Shallow Water Equations The three dimensional shallow water equations are reduced, by a process of vertical integration relating to the pertinent variables, to obtain equivalent equations in two dimensions An Unstructured Explicit Finite Element Model is adopted for solution of the governing equations The method of weighted residuals, in particular the Galerkin method, coupled with the finite element discretisation technique is then used to obtain a set of integral equations which can be assembled in a matrix form The domain is discretised with 9-noded lagrangian isoparametric elements Simpson’s 9-point integration rule, used to integrate over the 9-noded elements, leads to an explicit form of the assembled matrix (diagonal matrix) The above mentioned Unstructured Explicit Finite Element Method requires less computational resources and ensures higher order representation of the solution A computational domain (Bay of Bengal and northern part of the Indian Ocean) has been considered for simulation with an initial disturbance which resembles the type and location of the 2004 Indian Ocean Tsunami The wave elevations and deformations as well as time of travel of tsunami are reproduced The computed runup heights along Tamil Nadu coast of India were compared with the signature data and the agreement was found to be reasonable

Response characteristics of a discus shaped data buoy in nonlinear waves

Abstract: The response characteristics of a discus data buoy under the action of nonlinear waves are investigated through an experimental set-up in a wave tank. The details of the model, instrumentation, tes...