Nonlinear Hydroelastic Response of a Two-Dimensional Mat-Type VLFS by the Green-Naghdi Theory

2004 ◽  
Author(s):  
Dingwu Xia ◽  
R. Cengiz Ertekin ◽  
Jang Whan Kim
Keyword(s):  
Elastic Plate ◽  
Mechanical Energy ◽  
Beam Theory ◽  
Bending Moment ◽  
Open Water ◽  
Beam Equation ◽  
Two Dimensional ◽  
Jump Conditions ◽  
Numerical Predictions ◽  
Hydroelastic Response

The two-dimensional, nonlinear hydroelasticity of a mat-type VLFS is studied within the scope of linear beam theory for the structure and the nonlinear, Level I Green-Naghdi (GN) theory for the fluid. The beam equation and the GN equations are coupled through the kinematic and dynamic boundary conditions to obtain a new set of modified GN equations. These equations model long-wave motion beneath an elastic plate. A set of jump conditions that are necessary for the continuity (or the matching) of the solutions in the open water region and that under the structure is newly derived through the use of the postulated conservation laws of mass, momentum and mechanical energy. The resulting governing equations, subjected to the boundary and jump conditions, are solved by the finite-difference method in the time domain. The present model is applicable, for example, to the study of the hydroelastic response of a mat-type VLFS under the action of a solitary wave, or a frontal tsunami wave. Good agreement is observed between the present results and other published theoretical and numerical predictions, as well as experimental data. The nonlinear results show that consideration of nonlinearity is important for accurate predictions of the bending moment of the floating elastic plate. It is also found that the rigidity of the structure also greatly affects the bending moment and displacement of the structure in this nonlinear theory.

scholarly journals The Nonlinear Hydroelastic Response of a Semi-Infinite Elastic Plate Floating on a Fluid due to Incident Progressive Waves

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Ping Wang
Keyword(s):  
Incident Wave ◽  
Elastic Plate ◽  
Open Water ◽  
Angular Frequency ◽  
Physical Parameters ◽  
Thin Elastic Plate ◽  
Convergence Control ◽  
Progressive Waves ◽  
Analytical Series ◽  
Hydroelastic Response

The nonlinear hydroelastic response of very large floating structures (VLFSs) or an ice sheet floating on the surface of deep water, idealized as a semi-infinite thin elastic plate, is investigated analytically in the case of nonlinear incident waves. Assuming that the fluid is inviscid and incompressible and the motion is irrotational, we consider incident progressive waves with a given angular frequency within the framework of potential flow theory. With the aid of the homotopy analysis method (HAM), the convergent analytical series solutions are derived by solving the simultaneous equations in which we apply a convergence-control parameter to obtain convergent solutions with relatively few terms. The clear calculation results are represented to show nonlinear wave-plate interaction. The effects of different physical parameters, including incident wave amplitude, Young’s modulus, the thickness and density of the plate on the wave scattering, and the hydroelastic response of the floating plate, are considered. We find that the variations of the plate stiffness, thickness, and density greatly change amount of wave energy which is reflected into the open water region and is transmitted into the plate-covered region. Further, the hydroelastic response of the plate also can be affected by the amplitude of incident wave.

Reducing Hydroelastic Response of Interconnected Floating Beams Using Semi-Rigid Connections

2009 ◽  
Author(s):  
Chien Ming Wang ◽  
Muhammad Riyansyah ◽  
Yoo Sang Choo
Keyword(s):  
Fluid Motion ◽  
Beam Theory ◽  
Beam Equation ◽  
Floating Structure ◽  
Mechanical Joint ◽  
Hydroelastic Analysis ◽  
Hydroelastic Response ◽  
Frequency Domain Approach ◽  
Euler Bernoulli Beam ◽  
Element Method

This paper is concerned with the hydroelastic response of interconnected beams by a mechanical joint. A frequency domain approach is developed for the hydroelastic analysis. The fluid is modelled as an ideal fluid, whereas the beam is modelled by the Euler-Bernoulli beam theory. The boundary element method (BEM) and finite element method (FEM) are applied to solve the governing equations of fluid motion and beam equation of motion, respectively. This study investigates the design of the mechanical joint in reducing the hydroelastic response. The design involves varying the rotational stiffness and the location of such a mechanical joint to obtain a significant reduction of the hydroelastic response of the interconnected beams that model a longish very large floating structure (VLFS).

Recent Developments in Computational Methods for the Analysis of Ducted Propellers in Open Water

2019 ◽  
Vol 63 (4) ◽  
pp. 219-234
Author(s):  
João Baltazar ◽  
José A. C. Falcão de Campos ◽  
Johan Bosschers ◽  
Douwe Rijpkema
Keyword(s):  
Computational Methods ◽  
Open Water ◽  
Boundary Element Methods ◽  
Navier Stokes ◽  
Hydrodynamic Analysis ◽  
Numerical Predictions ◽  
Ducted Propeller ◽  
Recent Developments ◽  
Propeller Performance ◽  
Ducted Propellers

This article presents an overview of the recent developments at Instituto Superior Técnico and Maritime Research Institute Netherlands in applying computational methods for the hydrodynamic analysis of ducted propellers. The developments focus on the propeller performance prediction in open water conditions using boundary element methods and Reynolds-averaged Navier-Stokes solvers. The article starts with an estimation of the numerical errors involved in both methods. Then, the different viscous mechanisms involved in the ducted propeller flow are discussed and numerical procedures for the potential flow solution proposed. Finally, the numerical predictions are compared with experimental measurements.

Bending of an Infinite Beam on an Elastic Foundation

1937 ◽  
Vol 4 (1) ◽  
pp. A1-A7 ◽  
Author(s):  
M. A. Biot
Keyword(s):  
Elastic Foundation ◽  
Poisson Ratio ◽  
Elementary Theory ◽  
Three Dimensional ◽  
Bending Moment ◽  
Two Dimensional ◽  
Concentrated Load ◽  
Elastic Continuum ◽  
Infinite Beam ◽  
A Value

Abstract The elementary theory of the bending of a beam on an elastic foundation is based on the assumption that the beam is resting on a continuously distributed set of springs the stiffness of which is defined by a “modulus of the foundation” k. Very seldom, however, does it happen that the foundation is actually constituted this way. Generally, the foundation is an elastic continuum characterized by two elastic constants, a modulus of elasticity E, and a Poisson ratio ν. The problem of the bending of a beam resting on such a foundation has been approached already by various authors. The author attempts to give in this paper a more exact solution of one aspect of this problem, i.e., the case of an infinite beam under a concentrated load. A notable difference exists between the results obtained from the assumptions of a two-dimensional foundation and of a three-dimensional foundation. Bending-moment and deflection curves for the two-dimensional case are shown in Figs. 4 and 5. A value of the modulus k is given for both cases by which the elementary theory can be used and leads to results which are fairly acceptable. These values depend on the stiffness of the beam and on the elasticity of the foundation.

Global Hydroelastic Analysis of Pontoon-Type VLFS

2009 ◽  
Author(s):  
L. L. Jiao ◽  
M. Greco ◽  
O. M. Faltinsen
Keyword(s):  
Numerical Solutions ◽  
Parameter Analysis ◽  
Local Analysis ◽  
Two Dimensional ◽  
Numerical Wave Tank ◽  
Regular Waves ◽  
Hydroelastic Analysis ◽  
Air Cushion ◽  
Numerical Wave ◽  
Hydroelastic Response

A two-dimensional composite strategy given by Greco et al. [1] is applied to couple a linear global solution with a nonlinear local analysis. Globally a linear hydroelastic analysis is performed by an accurate Beam-On-Elastic-Foundation (BOEF) method. A parameter analysis of hydroelastic response of the structure is also carried out. Locally, a two-dimensional fully-nonlinear numerical wave tank (NWT) in combination with a Boundary Element Method (BEM) is developed to estimate the interaction between regular waves and the structure restrained from rigid and elastic motions. The effect of air cushion is considered. Present results are compared with experimental data and other numerical solutions.

Two-Dimensional Contact Analysis Using Trigonometric Polynomials: Some Early Verification Problems

2018 ◽  
Author(s):  
Gaurav Chauda ◽  
Daniel J. Segalman
Keyword(s):  
Half Plane ◽  
Frictional Contact ◽  
Contact Analysis ◽  
Trigonometric Polynomials ◽  
Elastic Contact ◽  
Two Dimensional ◽  
Contact Algorithm ◽  
Numerical Predictions ◽  
Interface Mechanics ◽  
Friction Models

A discretization strategy for elastic contact on a half plane has been devised to explore the significance of different friction models on joint-like interface mechanics. It is necessary to verify that discretization and accompanying contact algorithm on known solutions. An extensive comparison of numerical predictions of this model with corresponding 2-D elastic, frictional contact solutions from the literature is presented.

scholarly journals Flow patterns of shallow Palic Lake induced by the dominant winds

2012 ◽  
Vol 10 (1) ◽  
pp. 55-67
Author(s):  
Ljubomir Budinski ◽  
Djula Fabian
Keyword(s):  
Numerical Model ◽  
Flow Pattern ◽  
Coriolis Force ◽  
Wind Direction ◽  
Driving Forces ◽  
Open Water ◽  
Flow Patterns ◽  
Two Dimensional ◽  
Lake Model ◽  
Double Gyre

Studies of lake currents have highlighted that in case of stagnant waters winds are the dominant driving forces. This study is dealing with the influence of dominant winds on the flow pattern of Palic Lake. Action of steady winds of different directions has been tested on the lake by means of a two dimensional numerical model, while in addition to winds all other permanent factors like actual bathymetry, inflow and outflow as well the Coriolis force have been accounted for. The experiments have revealed that winds of different directions created corresponding characteristic flow patterns (in base plot), which were similar in cases of winds having opposite directions. However, in such cases the direction of flow was opposite. Moreover, the Palic Lake model produced the well known double-gyre flow pattern: in the coastal strip the direction of the current corresponded to the wind direction, while it was opposite in the domain of open water.

scholarly journals Evaluation of a polynya flux model by means of thermal infrared satellite estimates

2011 ◽  
Vol 52 (57) ◽  
pp. 52-60 ◽  
Author(s):  
Thomas Krumpen ◽  
Sascha Willmes ◽  
Miguel Angel Morales Maqueda ◽  
Christian Haas ◽  
Jens A. Hölemann ◽  
...  
Keyword(s):  
Conservation Laws ◽  
Open Water ◽  
Thermal Infrared ◽  
Ice Thickness ◽  
Two Dimensional ◽  
Moderate Resolution ◽  
Flux Model ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ice Production

AbstractWe test the ability of a two-dimensional flux model to simulate polynya events with narrow open-water zones by comparing model results to ice-thickness and ice-production estimates derived from thermal infrared Moderate Resolution Imaging Spectroradiometer (MODIS) observations in conjunction with an atmospheric dataset. Given a polynya boundary and an atmospheric dataset, the model correctly reproduces the shape of an 11 day long event, using only a few simple conservation laws. Ice production is slightly overestimated by the model, owing to an underestimated ice thickness. We achieved best model results with the consolidation thickness parameterization developed by Biggs and others (2000). Observed regional discrepancies between model and satellite estimates might be a consequence of the missing representation of the dynamic of the thin-ice thickening (e.g. rafting). We conclude that this simplified polynya model is a valuable tool for studying polynya dynamics and estimating associated fluxes of single polynya events.

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