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S. Nallayarasu

Bio: S. Nallayarasu is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Spar & Buoy. The author has an hindex of 9, co-authored 30 publications receiving 241 citations. Previous affiliations of S. Nallayarasu include Indian Institutes of Technology & National University of Singapore.

Papers
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Journal ArticleDOI
TL;DR: In this article, the estimation of the damping introduced by bilge keel is still largely based on empirical methods, however, the authors adopt the CFD approach to the estimation and validate the results with experiments conducted in a wave flume.

58 citations

Journal ArticleDOI
TL;DR: In this paper, the authors report three dimensional simulations of roll decay of a ship model, both with and without bilge keel, with experimental validation, and a good comparison of roll damping, natural period and added mass with experiments are obtained.

29 citations

Journal ArticleDOI
TL;DR: In this article, a simple method is proposed to decompose the composite wave record obtained from the wave reflection experiments in the wave flume, and the results obtained by the proposed method are compared with the two and three probe methods.

25 citations

Proceedings ArticleDOI
01 Jan 2011
TL;DR: In this paper, a 1: 100 scale model of a sparset was designed for a water depth of 245m with a payload of 10000 tonnes and the numerical analysis was carried out using ANSYS AQWA software.
Abstract: Spar technology has been used in offshore oil and gas exploration successfully for number of years for drilling, production and storage in deepwater. The motion response of floating structures especially the heave response in particular, is very important to the selection of suitable drilling and production equipments. Reduction of heave response can be achieved by attaching a heave damping plate to the keel of a Spar. This has been used in the past. Experimental and numerical studies on such devices of various diameters under regular waves has been carried out and presented. The experiments were conducted on a 1: 100 scale model of Spar designed for a water depth of 245m with a payload of 10000 tonnes and the numerical analysis was carried out using ANSYS AQWA software. Numerical and experimental values of RAOs for surge, pitch and heave compares reasonably well. Measured and numerical results of RAOs for surge, pitch and heave and the effect of diameter ratio, wave steepness, and mooring line pretension were presented and discussed. An optimum heave response is achieved when the heave plate diameter is 20% to 30% larger than the diameter of the spar.Copyright © 2011 by ASME

18 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a solution to the water-wave interaction with a submerged elastic plate of negligible thickness by the eigenfunction-matching method is presented, which depends on the solution of a special dispersion equation for a submerged plate and this is discussed in detail.
Abstract: We present a solution to the water-wave interaction with a submerged elastic plate of negligible thickness by the eigenfunction-matching method. The eigenfunction expansion depends on the solution of a special dispersion equation for a submerged elastic plate and this is discussed in detail. We show how the solution can be calculated for the case of normal incidence on a semi-infinite plate in two spatial dimensions and then extend this solution to obliquely incident waves, to a plate of finite length and to a circular finite plate in three dimensions. Numerical calculations showing various properties of the solutions are presented and a near-orthogonality relation for the eigenfunctions is used to derive an energy-balance relation.

86 citations

Journal ArticleDOI
TL;DR: In this paper, a model of a semi-submersible floating offshore wind turbine with a vertical flap at its edge is presented, and the influence of the flap on the hydrodynamic coefficients is investigated through a results comparison with the plain solid one.

78 citations

Journal Article
TL;DR: The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years as mentioned in this paper, however, performance can still fall short of expectations due to fundamental performance limitations and large variations of the spectral characteristics of wave-induced roll motion.
Abstract: The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years. Performance, however, can still fall short of expectations because of difficulties associated with control system designs, which have proven to be far from trivial due to fundamental performance limitations and large variations of the spectral characteristics of wave-induced roll motion. This tutorial paper presents an account of the development of various ship roll motion control systems together with the challenges associated with their design. It discusses the assessment of performance and the applicability of different mathematical models, and it surveys the control methods that have been implemented and validated with full scale experiments. The paper also presents an outlook on what are believed to be potential areas of research within this topic.

75 citations

Journal ArticleDOI
TL;DR: In this article, the applicability of a multiphase Reynolds Averaged Navier-Stokes (RANS) numerical model for simulating the interaction between an OWC and regular and irregular waves is investigated.

66 citations

20 Sep 1993
TL;DR: In this article, the authors present an approach for the analysis and design of tubular structures, based on the A.W.S. code, and propose new rules for tubular connections.
Abstract: 1. Introduction to Tubular Structures. Attributes of Tubes. Architectural and Structural Forms. The Need for an Integrated Approach. Author's Viewpoint for this Monograph. Tubulars as Structural Members. Simple Welded Joints. 2. Conceptual Basis for the Design Rules. Definitions. Failure modes of tubular connections. General procedures for analysis and design. Design simplifications. Stresses in welds. 3. Static Strength of Circular Section Joints. Early work on T-, Y-, and K-connections. Lessons from field failures. Overcoming the beta paradox. Empirical punching shear design equation. Understanding the sources of reserve strength. Further evolution of the A.W.S. code. Final form. Design charts. 4. Fatigue Design. Levels of analysis. Hot spot stress. Stress concentration factors (SCF). S-N curves. Comparisons with international rules and data. 5. Tubular Connections Involving Non-Circular Sections. Box connections - existing A.W.S. rules. Box connections - proposed new rules. Hybrid connections. Special topics. Fatigue box connections. 6. Special Topics for Circular Section Joints. Overlapping connections. Multi-planar connections. Grouted connections. Internally stiffened tubular connections. 7. Fatigue Size and Profile Effects. Fracture toughness. Lamellar tearing. Role of redundancy. Non-destructive inspection criteria. 8. Construction System. Material selection. Tube manufacture. Connection layout. Welded joint design. Welder and procedure qualification. Prefabrication. Assembly. Inspection. Appendices. 1. Symbols and notation. 2. Design revisions, tubular structures. 3. Notch toughness task group, proposed revisions for AWS D1.1. Index.

66 citations