scholarly journals Non-negative Intensity for Target Strength Identification in Marine Ecosystem Research

2021 ◽  
Author(s):  
Daipei Liu ◽  
Steffen Marburg ◽  
Nicole Kessissoglou
Keyword(s):  
Complex Geometry ◽  
Marine Ecosystem ◽  
Elastic Shell ◽  
Target Strength ◽  
The Finite Element Method ◽  
Individual Organism ◽  
Ecosystem Research ◽  
Weak Scattering ◽  
Fully Coupled ◽  
Element Method

In this paper, we propose non-negative intensity (NNI) as an alternative intensity-based technique for target strength identification in marine ecosystem research. NNI identifies local surface regions of a body with positive-only sound power contributions. NNI is employed for sound scattering by fluid-loaded, fluid-filled elastic structures with weak scattering boundary conditions. Three numerical case studies are presented for which fully coupled fluid-structure interaction models based on the finite element method (FEM) and the boundary element method (BEM) are developed. To validate the three-way coupling between the structural and fluid domains, an elastic shell submerged in water and filled with different internal fluids is initially considered. Results for the scattered acoustic intensity obtained numerically are compared with analytical results from the literature. Models representing Antarctic krill of simple and complex geometry are developed. A 3×3 cylinder array representing a simplified aggregation of krill is also presented. Target strength is calculated using both the scattered intensity and NNI for different incident excitation angles. Results for NNI identify the surface regions of an individual organism or group of organisms with the greatest contribution to the scattered sound at the target strength locations.

Numerical implementation of finite-element method of control volume using irregular mesh

2010 ◽  
Vol 7 ◽  
pp. 98-108
Author(s):  
Yu.A. Gafarova
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Delaunay Triangulation ◽  
Complex Geometry ◽  
Control Volume ◽  
Test Case ◽  
The Finite Element Method ◽  
Irregular Mesh ◽  
Discrete Analogues ◽  
Element Method

To solve problems with complex geometry it is considered the possibility of application of irregular mesh and the use of various numerical methods using them. Discrete analogues of the Beltrami-Mitchell equations are obtained by the control volume method using the rectangular grid and the finite element method of control volume using the Delaunay triangulation. The efficiency of using the Delaunay triangulation, Voronoi diagrams and the finite element method of control volume in a test case is demonstrated.

scholarly journals The Finite Element Method Applied to the Magnetostatic and Magnetodynamic Problems

2020 ◽  
Author(s):  
Dang Quoc Vuong ◽  
Bui Minh Dinh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electric Fields ◽  
Complex Geometry ◽  
Analytic Method ◽  
The Finite Element Method ◽  
Electromagnetic Problems ◽  
Common Technique ◽  
The Finite Difference Method ◽  
Element Method

Modelling of realistic electromagnetic problems is presented by partial differential equations (FDEs) that link the magnetic and electric fields and their sources. Thus, the direct application of the analytic method to realistic electromagnetic problems is challenging, especially when modeling structures with complex geometry and/or magnetic parts. In order to overcome this drawback, there are a lot of numerical techniques available (e.g. the finite element method or the finite difference method) for the resolution of these PDEs. Amongst these methods, the finite element method has become the most common technique for magnetostatic and magnetodynamic problems.

New Boundary Treatment in the Finite Element Model Using the Shallow Water Equation

2012 ◽  
Vol 446-449 ◽  
pp. 2694-2698
Author(s):  
Tae Hwa Jung
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Complex Geometry ◽  
Numerical Technique ◽  
Shallow Water Equation ◽  
Element Model ◽  
The Finite Element Method ◽  
Boundary Treatment ◽  
The Finite Element Model ◽  
Element Method

Effective numerical technique for treatment of inclined boundary in the finite element method was introduced. Finite element method was frequently used to analyze hydraulic phenomena in the coastal zone because it can be applied to irregular and complex geometry. In this study, we introduced the way to treat the boundary condition over an inclined bottom.

scholarly journals NUMERICAL CALCULATION OF THE STIFFNESS OF THE ELASTIC BLOCK OF THE HYDRAULIC SUPPORT SHELL BY THE FINITE ELEMENT METHOD

2021 ◽  
pp. 22-35
Author(s):  
B.A. Gordeev ◽  
S.N. Ohulkov ◽  
A.N. Osmekhin ◽  
A.S. Plekhov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Shell ◽  
Safety Margin ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Hydraulic Support ◽  
Subsequent Determination ◽  
Stiffness And Damping ◽  
Element Method

The article presents the calculation of the stiffness of the elastic shell of hydraulic supports by the finite element method. This calculation is necessary to know the safety margin of the rubber shell, since with an increase in the resulting vibration, the service life of the MR-hydraulic support decreases, leading to its destruction [1, 2]. The purpose of this study is to calculate and evaluate the maximum shear deformations of the rubber shell of the hydraulic support necessary for the subsequent determination of the stiffness and damping of the hydraulic support at resonant frequencies. The finite element method is used to estimate the maximum shear deformations of the rubber shell of the hydraulic support caused by variable loads.

Modeling PEM Fuel Cell Performance Using the Finite-Element Method and a Fully-Coupled Implicit Solution Scheme via Newton’s Technique

2006 ◽  
Author(s):  
Ken S. Chen ◽  
Michael A. Hickner
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fuel Cell ◽  
Current Distribution ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
The Finite Element Method ◽  
Solution Scheme ◽  
Fully Coupled ◽  
Element Method

A numerical model that employs the finite-element method and a fully-coupled implicit solution scheme via Newton’s technique is presented for simulating the performance of polymer-electrolyte-membrane (PEM) fuel cells. With our model, solved are the multi-dimensional momentum, mass & species, and charge conservation equations that govern, respectively, pressure-gradient driven flows along the gas flow channels (GFCs) and within the gas diffusion layers (GDLs), species transport along GFCs and within GDLs, and proton and water transport within the membrane as well as the ButlerVolmer constitutive equations describing the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR). For simplicity, the present version of our model considers PEM fuel cell operation as isothermal and water present as vapor, and treats the anode and cathode catalyst layers as respective interfaces at which HOR and ORR take place. With our numerical approach, all governing equations are solved simultaneously and quadratic convergence is ensured due to the use of Newton’s method with an analytical Jacobian. To demonstrate the utility of our computational approach, computed predictions of velocity field, contours of hydrodynamic pressure and molar concentrations of hydrogen, oxygen and water species, and current distribution and polarization (or I-V) curves from a two-dimensional case study of a simplified PEM fuel cell are presented. To help assess the validity of our PEM fuel cell model, measurements of current distribution and polarization curves were performed using a segmented PEM fuel cell, and the resultant experimental data as well as that from the literature are compared with computed predictions.

Calculation on Acoustic Scattering of Viscoelastic Layer Coupling with Elastic Shell

2012 ◽  
Vol 248 ◽  
pp. 107-113
Author(s):  
Zhong Kun Jin ◽  
Tong Qing Wang
Keyword(s):  
Boundary Condition ◽  
Spherical Shell ◽  
Elastic Shell ◽  
Acoustic Scattering ◽  
Impedance Boundary Condition ◽  
Target Strength ◽  
Viscoelastic Layer ◽  
Impedance Boundary ◽  
Elastic Spherical Shell ◽  
Element Method

This paper is devoted to numerical research on coupling between elastic spherical shell and the coated viscoelastic layer as well as the scattering of incident plane wave by the double-layer spherical shell. The scattering sound field is solved based on impedance boundary condition by boundary element method (BEM). Dynamic finite element method (FEM) is used to numerically simulate the acoustic impedance boundary condition which involved in the coupled spherical shell. Impedance distribution for elastic spherical shell and elastic spherical shell coated viscoelastic layer is calculated and its effect on the target strength (TS) is discussed finally.

Sign in / Sign up

Export Citation Format

Share Document