A Submerged Compliant Breakwater

1992 ◽  
Vol 114 (2) ◽  
pp. 83-90 ◽  
Author(s):  
A. N. Williams ◽  
P. T. Geiger ◽  
W. G. McDougal
Keyword(s):  
Flexural Rigidity ◽  
Numerical Technique ◽  
Structural Parameters ◽  
Unit Length ◽  
Fluid Velocity ◽  
Fluid Motion ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Numerical Results ◽  
Small Scale

A numerical technique is utilized to investigate the dynamics of a submerged compliant breakwater consisting of a flexible, beamlike structure anchored to the seabed and kept under tension by a small buoyancy chamber at the tip. The fluid motion is idealized as linearized, two-dimensional potential flow and the equation of motion of the breakwater is taken to be that of a one-dimensional beam of uniform flexural rigidity and mass per unit length subjected to a constant axial force. The boundary integral equation method is applied to the fluid domain, modifications are made to the basic formulation to account for the zero thickness of the idealized structure and the singularity in the fluid velocity which occurs at the breakwater tip. The dynamic behavior of the breakwater is described through an appropriate Green function. Numerical results are presented which illustrate the global influence of the tip singularity on the solution and the effects of the various wave and structural parameters on the efficiency of the breakwater as a barrier to wave action. Small-scale physical model tests were also carried out to validate the foregoing theory. In general, the agreement between experimental and numerical results was reasonable, but with considerable scatter.

Floating Membrane Breakwater

1996 ◽  
Vol 118 (1) ◽  
pp. 46-52 ◽  
Author(s):  
A. N. Williams
Keyword(s):  
Wave Reflection ◽  
Structural Parameters ◽  
Unit Length ◽  
Fluid Motion ◽  
Integral Equation Method ◽  
Equation Of Motion ◽  
Boundary Integral ◽  
Mooring Line ◽  
Hydrodynamic Properties ◽  
One Dimensional

The hydrodynamic properties of a flexible floating breakwater consisting of a membrane structure attached to a small float restrained by moorings are investigated theoretically. The tension in the membrane is achieved by hanging a clump weight from its lower end. The fluid motion is idealized as linearized, two-dimensional potential flow and the equation of motion of the breakwater is taken to be that of a one-dimensional membrane of uniform mass per unit length subjected to a constant axial force. The boundary integral equation method is applied to the fluid domain, and the dynamic behavior of the breakwater is also described through an appropriate Green function. Numerical results are presented which illustrate the effects of the various wave and structural parameters on the efficiency of the breakwater as a barrier to wave action. It is found that the wave reflection properties of the structure depend strongly on the membrane length, the magnitude of the clump weight, and the mooring line stiffness, while the membrane weight and excess buoyancy of the system are of lesser importance.

Analysis of Clamped Plates on Elastic Foundation by the Boundary Integral Equation Method

1984 ◽  
Vol 51 (3) ◽  
pp. 574-580 ◽  
Author(s):  
J. T. Katsikadelis ◽  
A. E. Armena`kas
Keyword(s):  
Integral Equation ◽  
Integral Equations ◽  
Elastic Foundation ◽  
Boundary Integral Equation ◽  
Numerical Evaluation ◽  
Boundary Integral Equations ◽  
Numerical Technique ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Plates On Elastic Foundation

In this investigation the boundary integral equation (BIE) method with numerical evaluation of the boundary integral equations is developed for analyzing clamped plates of any shape resting on an elastic foundation. A numerical technique for the solution to the boundary integral equations is presented and numerical results are obtained and compared with those existing from analytical solutions. The effectiveness of the BIE method is demonstrated.

Analysis of Cracked Body Strengthened by Adhesively Bonded Patches by BEM-FEM Coupling

2020 ◽  
pp. 2041013
Author(s):  
Binh V. Pham ◽  
Thai Binh Nguyen ◽  
Jaroon Rungamornrat
Keyword(s):  
Numerical Technique ◽  
Three Dimensional ◽  
Direct Calculation ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Singular Boundary ◽  
Adhesively Bonded ◽  
Crack Face ◽  
Finite Element Procedure ◽  
The Right

This paper presents an efficient numerical technique capable of handling the stress analysis of three-dimensional cracked bodies strengthened by adhesively bonded patches. The proposed technique is implemented within the framework of the coupling of the weakly singular boundary integral equation method and the standard finite element procedure. The former is applied to efficiently treat the elastic body containing cracks, whereas the latter is adopted to handle both the adhesive layers and patches. The approximation of the near-front relative crack-face displacement is enhanced by using local interpolation functions that can capture the right asymptotic behavior. This also offers the direct calculation of the stress intensity factors along the crack front. A selected set of results is reported to demonstrate the capability of the proposed technique and the influence of various parameters on the performance of the strengthening.

Anisotropic stress analysis of inclusion problems using the boundary integral equation method

1992 ◽  
Vol 27 (2) ◽  
pp. 67-76 ◽  
Author(s):  
C L Tan ◽  
Y L Gao ◽  
F F Afagh
Keyword(s):  
Integral Equation ◽  
Stress Analysis ◽  
Boundary Integral Equation ◽  
Numerical Technique ◽  
Integral Equation Method ◽  
Anisotropic Elasticity ◽  
Boundary Integral ◽  
Element Formulation ◽  
Inclusion Problems ◽  
Structural Applications

Numerical methods for stress analysis are increasingly being employed in the micromechanics of solids. In this paper, the boundary integral equation (BIE) method for two-dimensional general anisotropic elasticity, based on the quadratic isoparametric element formulation, is extended to treating some inclusion problems. All the cases analysed involved an elliptical zirconia inclusion in an alumina matrix, noting that ZrO2–Al2O3 is an advanced ceramic increasingly used in structural applications. The BIE results are compared with those calculated using Eshelby's equivalent inclusion approach where possible, and excellent agreements between them are obtained. The present work demonstrates the suitability of using this numerical technique for analysing such problems and, in particular, the ease with which it may be used even in the case of general anisotropy.

scholarly journals Numerical study on the impulsive growth of a gaseous plug inside a cylindrical vein with compliant coating

Bioimpacts ◽  
2017 ◽  
Vol 8 (4) ◽  
pp. 271-279
Author(s):  
Mohammad T. Shervani-Tabar ◽  
Babak Farzaneh ◽  
Reza Ahrabi ◽  
Seyed E. Razavi
Keyword(s):  
Numerical Study ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Numerical Results ◽  
Compliant Coating ◽  
Internal Wall ◽  
Maximum Volume ◽  
Bubble Generation ◽  
Rigid Cylinder ◽  
The Impact

Introduction: Employing of gaseous plugs inside a vein for preventing of blood flow to the damaged or cancerous tissues has been known as a gas embolism in the medicine. In this research, a numerical investigation has been carried out on the delivery of the liquid drug DDFP, encapsulated in the microlipid-coated spheres (MLCSs), to target the human vein for construction of the gaseous plug inside the veins. Methods: The encapsulated liquid drug DDFP were delivered to the vein by injection of an emulsion. Releasing of the liquid drug DDFP results in an explosive growth of a gaseous plug inside the vein. The targeted vein was served as a rigid cylinder with a compliant coating. The boundary integral equation method has been employed for the numerical simulation of the hydrodynamic behavior of the gaseous plug inside the vein. Results: Numerical results showed that in the case of a rigid cylinder vein with an internal compliant coating, the maximum volume of the gaseous plug was smaller than the case of just a rigid cylinder vein. Furthermore, its elapsed time from the instant of bubble generation to the instant when the bubble reaches its maximum volume was shorter. Numerical results also showed that the compliant coating on the internal wall of the rigid cylindrical vein had a tendency of reducing the impact of the explosive growth of the gaseous plug. Conclusion: This numerical research showed that the compliant coating on the internal wall of the rigid cylindrical vein had the tendency of reducing the impact of the impulsive growth of the gaseous plug. Therefore, in the case of having severed arteriosclerosis, treatment of the cancerous or damaged tissues by use of the gaseous embolism must be done very carefully in order to prevent the hazardous effects of the gaseous plug’s impulsive growth.

scholarly journals Dynamic Response of a Cracked Viscoelastic Anisotropic Plane Using Boundary Elements and Fractional Derivatives

2018 ◽  
Vol 48 (2) ◽  
pp. 24-49 ◽  
Author(s):  
Tsviatko V. Rangelov ◽  
Petia S. Dineva ◽  
George D. Manolis
Keyword(s):  
Wave Propagation ◽  
Bulk Material ◽  
Numerical Technique ◽  
Surface Elasticity ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Nano Scale ◽  
Viscoelastic Wave Propagation ◽  
Macro Scale ◽  
Modelling Effort

Abstract The aim of this study is to develop an efficient numerical technique using the non-hypersingular, traction boundary integral equation method (BIEM) for solving wave propagation problems in an anisotropic, viscoelastic plane with cracks. The methodology can be extended from the macro-scale with certain modifications to the nano-scale. Furthermore, the proposed approach can be applied to any type of anisotropic material insofar as the BIEM formulation is based on the fundamental solution of the governing wave equation derived for the case of general anisotropy. The following examples are solved: (i) a straight crack in a viscoelastic orthotropic plane, and (ii) a blunt nano-crack inside a material of the same type. The mathematical modelling effort starts from linear fracture mechanics, and adds the fractional derivative concept for viscoelastic wave propagation, plus the surface elasticity model of M. E. Gurtin and A. I. Murdoch, which leads to nonclassical boundary conditions at the nano-scale. Conditions of plane strain are assumed to hold. Following verification of the numerical scheme through comparison studies, further numerical simulations serve to investigate the dependence of the stress intensity factor (SIF) and of the stress concentration factor (SCF) that develop in a cracked inhomogeneous plane on (i) the degree of anisotropy, (ii) the presence of viscoelasticity, (iii) the size effect with the associated surface elasticity phenomena, and (iv) finally the type of the dynamic disturbance propagating through the bulk material.

scholarly journals The Benefits of Combining Global and Local Data—A Showcase for Valuation and Mapping of Mangrove Climate Regulation and Food Provisioning Services within a Protected Area in Pará, North Brazil

Land ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 432
Author(s):  
Robin Gutting ◽  
Ralf-Uwe Syrbe ◽  
Karsten Grunewald ◽  
Ulf Mehlig ◽  
Véronique Helfer ◽  
...  
Keyword(s):  
Global Climate ◽  
Structural Parameters ◽  
Management Strategies ◽  
Small Scale ◽  
Mangrove Forests ◽  
Food Provisioning ◽  
Local Data ◽  
Climate Regulation ◽  
North Brazil ◽  
Species Specific

Mangrove forests provide a large variety of ecosystem services (ES) to coastal societies. Using a case study focusing on the Ajuruteua peninsula in Northern Brazil and two ES, food provisioning (ES1) and global climate regulation (ES2), this paper proposes a new framework for quantifying and valuing mangrove ES and allow for their small-scale mapping. We modelled and spatialised the two ES from different perspectives, the demand (ES1) and the supply (ES2) side respectively. This was performed by combining worldwide databases related to the global human population (ES1) or mangrove distribution and canopy height (ES2) with locally derived parameters, such as crab catches (ES1) or species-specific allometric equations based on local estimates of tree structural parameters (ES2). Based on this approach, we could estimate that the area delivers the basic nutrition of about 1400 households, which equals 2.7 million USD, and that the mangrove biomass in the area contains 2.1 million Mg C, amounting to 50.9 million USD, if it were paid as certificates. In addition to those figures, we provide high-resolution maps showing which areas are more valuable for the two respective ES, information that could help inform management strategies in the future.

The inverse elastic scattering by an impenetrable obstacle and a crack

2020 ◽  
Author(s):  
Jianli Xiang ◽  
Guozheng Yan
Keyword(s):  
Mixed Type ◽  
Scattering Problem ◽  
Inverse Scattering Problem ◽  
Field Operator ◽  
Integral Equation Method ◽  
Factorization Method ◽  
Boundary Integral ◽  
Far Field ◽  
Direct Scattering ◽  
Time Harmonic

Abstract This paper is concerned with the inverse scattering problem of time-harmonic elastic waves by a mixed-type scatterer, which is given as the union of an impenetrable obstacle and a crack. We develop the modified factorization method to determine the shape of the mixed-type scatterer from the far field data. However, the factorization of the far field operator $F$ is related to the boundary integral matrix operator $A$, which is obtained in the study of the direct scattering problem. So, in the first part, we show the well posedness of the direct scattering problem by the boundary integral equation method. Some numerical examples are presented at the end of the paper to demonstrate the feasibility and effectiveness of the inverse algorithm.

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