A general linear hydroelasticity theory of floating structures moving in a seaway

1986 ◽  
Vol 316 (1538) ◽  
pp. 375-426 ◽  
Keyword(s):  
Fluid Flow ◽  
Finite Elements ◽  
Linear Theory ◽  
Three Dimensional ◽  
Elastic Beam ◽  
Offshore Structures ◽  
Elastic Structure ◽  
Complicated Shape ◽  
Floating Structures ◽  
General Method

The dynamics of an elastic beam floating on the surface of disturbed water has formed the basis of a fairly comprehensive linear theory of hydroelastic behaviour of ships in waves. The existing theory cannot easily be extended to floating vehicles of more complicated shape (such as semi-submersibles), or to fixed offshore structures. A general method is presented, by which finite elements permit any three-dimensional elastic structure to be admitted in a linear hydroelastic theory. Sinusoidal waves provide the excitation of the structure and the fluid flow is three-dimensional. Some examples are given which illustrate the use of the theory and expose behaviour that has not been encountered hitherto.

The Effect of Aircushion Division on the Structural Loads of Large Floating Offshore Structures

2007 ◽  
Author(s):  
J. L. F. van Kessel ◽  
J. A. Pinkster
Keyword(s):  
Water Surface ◽  
Three Dimensional ◽  
Potential Method ◽  
Offshore Structures ◽  
Bending Moments ◽  
Shear Forces ◽  
Floating Structures ◽  
The Mean ◽  
Wave Induced

The effect of aircushion division on the structural loads of large floating offshore structures is described and compared with that of a rectangular barge having the same dimensions. Calculations are based on a linear three-dimensional potential method using a linear adiabatic law for the air pressures inside the cushions. The water surface within the aircushions and the mean wetted surface are modelled by panel distributions representing oscillating sources. In the presented cases the structural loads include the wave induced bending moments and shear forces along the length of the structure. Aircushions significantly influence the behaviour of large floating structures in waves and consequently reduce the bending moments. The internal loads of different configurations of aircushion supported structures are described and compared with those of a rectangular barge having the same dimensions. The significant reduction of the bending moments shows that aircushion support can be of interest for large floating structures.

scholarly journals Alternative derivation of the higher-order constitutive model for six-parameter elastic shells

2021 ◽  
Vol 72 (2) ◽  
Author(s):  
Mircea Bîrsan
Keyword(s):  
Energy Density ◽  
Constitutive Model ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Shell Theory ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Classical Shell Theory ◽  
Three Dimensional Elasticity ◽  
General Method

AbstractIn this paper, we present a general method to derive the explicit constitutive relations for isotropic elastic 6-parameter shells made from a Cosserat material. The dimensional reduction procedure extends the methods of the classical shell theory to the case of Cosserat shells. Starting from the three-dimensional Cosserat parent model, we perform the integration over the thickness and obtain a consistent shell model of order $$ O(h^5) $$ O ( h 5 ) with respect to the shell thickness h. We derive the explicit form of the strain energy density for 6-parameter (Cosserat) shells, in which the constitutive coefficients are expressed in terms of the three-dimensional elasticity constants and depend on the initial curvature of the shell. The obtained form of the shell strain energy density is compared with other previous variants from the literature, and the advantages of our constitutive model are discussed.

scholarly journals Fast multipole solvers for three-dimensional radiation and fluid flow problems

1999 ◽  
Vol 7 ◽  
pp. 408-417 ◽  
Author(s):  
J. H. Strickland ◽  
L. A. Gritzo ◽  
R. S. Baty ◽  
G. F. Homicz ◽  
S. P. Burns
Keyword(s):  
Fluid Flow ◽  
Three Dimensional ◽  
Fast Multipole ◽  
Flow Problems

On the Flexural-Torsional Behavior of a Straight Elastic Beam Subject to Terminal Moments

1993 ◽  
Vol 60 (2) ◽  
pp. 498-505 ◽  
Author(s):  
Z. Tan ◽  
J. A. Witz
Keyword(s):  
Coordinate System ◽  
Cross Section ◽  
Equilibrium Equation ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Elastic Beam ◽  
Cartesian Coordinate System ◽  
Kinematic Constraints ◽  
Torsional Behavior ◽  
Cartesian Coordinate

This paper discusses the large-displacement flexural-torsional behavior of a straight elastic beam with uniform circular cross-section subject to arbitrary terminal bending and twisting moments. The beam is assumed to be free from any kinematic constraints at both ends. The equilibrium equation is solved analytically with the full expression for curvature to obtain the deformed configuration in a three-dimensional Cartesian coordinate system. The results show the influence of the terminal moments on the beam’s deflected configuration.

Laminar Fluid Flow Around Two Wall-Mounted Blocks of Different Size

2009 ◽  
Author(s):  
Mohammad Mehdi Tavakol ◽  
Mohammad Eslami
Keyword(s):  
Fluid Flow ◽  
Free Stream ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Bluff Bodies ◽  
Wake Region ◽  
Science And Engineering ◽  
Vortical Structures ◽  
Laminar Fluid Flow ◽  
Pressure Distributions

Fluid flow around single or multiple bluff bodies mounted on a surface has great significance in science and engineering. Understanding the characteristics of different vortices formed around wall-mounted bodies is quite necessary for different applications. Although the case of a single surface mounted cube has been studied extensively, only little attention has been paid to the flow around two or more rectangular blocks in array. Therefore, a CFD code is developed to calculate three dimensional steady state laminar fluid flow around two cuboids of arbitrary size and configuration mounted on a surface in free stream conditions. The employed numerical scheme is finite volume and SIMPLE algorithm is used to treat pressure and velocity coupling. Results are presented for two rectangular blocks of the different size mounted on a surface in various inline arrangements. Streamlines are plotted for blocks of different size ratio. Velocity and pressure distributions are also plotted in the wake region behind the obstacles. It is shown that how the behavior of flow field and vortical structures depend on the respective size and location of the larger block in comparison with the case of two inline wall mounted cubes of the same size.

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