Now showing 1 - 4 of 4
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    Three-dimensional finite element analysis of the diffraction-radiation problem of hydrodynamically compact structures
    (01-01-1995) ;
    Vendhan, C. P.
    The finite element method for solving the linear floating body hydrodynamic problem is considered with a hierarchy of boundary damper options for modelling the far field. The computer program is validated using two simple examples for which added mass and damping coefficients are computed over a wide range of frequencies. The program is applied to the ISSC TLP, being a typical practical example for which a large scatter in numerical results is reported in the literature. © 1995.
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    Analysis of diffraction-radiation problem of a twin-hull barge system
    (01-01-1995) ;
    Vendhan, C. P.
    Ocean wave is an important marine environmental phenomena which influences the performance of a marine structure. This necessitates a detailed hydrodynamic study of the wave-structure interaction problem. In the present work the finite element method has been demonstrated as an effective tool to solve the complex linearised three-dimensional hydrodynamic problem. The developed software has been validated for regular bodies and applied to a multi-body (twin-barge) system. © 1995 IOS. All Rights Reserved.
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    Publication
    Study of water wave diffraction around cylinders using a finite-element model of fully nonlinear potential flow theory
    (17-02-2017)
    Kumar, P. Sunny
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    Vendhan, C. P.
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    Numerical models employing the fully nonlinear potential flow theory have been studied for over three decades. Adopting the mixed Eulerian–Lagrangian formulation, solution over the fluid domain has been obtained using both the boundary integral/element and finite-element (FE) methods, the latter being the main focus of the present paper. The FE model is derived employing a variational formulation. The main highlight of the FE model developed pertains to the calculation of fluid particle velocities using a C0-type FE solution. The velocity calculation procedure is analogous to the traditional stress calculation approach used in FE analysis of solid mechanics problems and is applicable to unstructured isoparametric hexahedral meshes. The numerical model has been applied to evaluate nonlinear diffraction forces on single cylinder problems and Fourier decomposition has been applied to the pressure force time history obtained. The first-order diffraction forces and moments derived from the present nonlinear model compare very well with literature results. The second-order oscillating and mean forces as well as the second-order mean moments compare fairly well with literature results. However, significant deviations are seen in the second-order oscillating moments. It is conjectured that side wall reflections of higher-order wave components in the numerical wave tank might be responsible for this. This aspect merits further investigation.
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    Publication
    Finite element analysis of nonlinear water wave-body interaction- computational issues
    (01-12-2012)
    Vendhan, C. P.
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    Sunny Kumar, P.
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    Design of floating structures exposed to water waves often requires nonlinear analysis because of high wave steepness and large body motion. In this context, Mixed Eulerian-Lagrangian (MEL) methods for nonlinear water wave problems based on the potential flow theory have been studied extensively. Here, the Laplace equation with Dirichlet boundary condition on the free surface is solved using the boundary integral method, and a time integration method is used to find the particle displacements and velocity potential on the free surface. Finite element methods based on the MEL formulation have been developed in the 90s. Several researchers have pursued this approach, addressing the various challenges thrown open, such as velocity computation, pressure computation on moving surfaces, remeshing of the computational domain, smoothing and imposition of radiation condition. Apart from these, the implementation of the FE model in particular involves several computational issues such as element property computation, solution of large banded matrix equations, and efficient organization of computer storage, all of which are crucial for the computational tool to become successful. A study of these aspects constitutes the primary focus of the present work. The authors have recently developed a 3-D FE model employing the MEL formulation, which has been applied to predict waves in a flume and basin. The fluid domain is discretized using 20-node hexahedral elements. The free surface equations are solved in the time domain employing the three-point Adams-Bashforth method. Validation of the numerical model and relative computation times for salient steps in the FE model are discussed in the paper. Copyright © 2012 by ASME.