A Three-Dimensional Modeling of Multidirectional Random Wave Interactions by Multiple Rectangular Submarine Pits

2004 ◽  
Author(s):  
Hong Sik Lee ◽  
A. Neil Williams ◽  
Sung Duk Kim
Keyword(s):  
Numerical Model ◽  
Velocity Potential ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Integral Approach ◽  
Random Wave ◽  
Random Surface ◽  
Directional Spectrum ◽  
Practical Applications ◽  
Three Dimensional Modeling

A three-dimensional numerical model is presented to predict the interactions of multidirectional random surface waves with one or more rectangular submarine pits. The water depth in the fluid region exterior to the pits is taken to be uniform. The three-dimensional Green function in the boundary integral equation, obtained by Green’s second identity, has been used for the solution of the velocity potential and its derivative in fluid interface between regions, and also a form of the Fourier expansion is utilized for the solution of the velocity potential in the interior region. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The present method is based on the cumulative superposition of linear diffraction solutions obtained by a three-dimensional boundary integral approach. The results of the present model have been compared with those of previous theoretical studies for both regular and random wave diffraction by single or multiple pits. Reasonable agreement was consistently obtained in all cases. In accordance with good agreement from these comparisons, it is concluded that the present numerical model may accurately be utilized to predict the three-dimensional wave field around multiple submarine pits or navigation channels in many practical applications.

The Diffraction of Multidirectional Random Waves by Trapezoidal Submarine Pits

2003 ◽  
Author(s):  
Hong Sik Lee ◽  
A. Neil Williams ◽  
Sung Duk Kim
Keyword(s):  
Numerical Model ◽  
Wave Diffraction ◽  
Boundary Integral ◽  
Random Wave ◽  
Linear Wave ◽  
Wave System ◽  
Random Waves ◽  
Random Surface ◽  
Directional Spectrum ◽  
Integral Equation Approach

A numerical model is presented to predict the interaction of multidirectional random surface waves with one or more trapezoidal submarine pits. In the present formulation, each pit may have a different side slope, while the four side slopes at the interior edge of any given pit are assumed equal. The water depth in the fluid region exterior to the pits is taken to be uniform, and the solution method for a random wave system involves the superposition of linear-wave diffraction solutions based on a two-dimensional boundary integral equation approach. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The results of the present numerical model have been compared with those of previous theoretical studies for regular and random wave diffraction by single or multiple rectangular pits. Reasonable agreement was obtained in all cases. Based on these comparisons it is concluded that the present numerical model is an accurate and efficient tool to predict the wave field around multiple submarine pits of trapezoidal section in many practical situations.

The Diffraction of Multidirectional Random Waves by Rectangular Submarine Pits

2004 ◽  
Vol 126 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Hong Sik Lee ◽  
A. Neil Williams
Keyword(s):  
Water Wave ◽  
Wave Theory ◽  
Boundary Integral ◽  
Integral Approach ◽  
Two Dimensional ◽  
Random Waves ◽  
Discrete Form ◽  
Random Surface ◽  
Directional Spectrum ◽  
Dimensional Boundary

The diffraction of multidirectional random surface waves with one or more rectangular submarine pits is investigated theoretically. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The numerical model involves the superposition of regular-wave diffraction solutions based on linearized shallow water wave theory obtained by a two-dimensional boundary integral approach for water of uniform depth. Numerical results are presented for multi-directional random waves that illustrate the effect of the various wave and pit parameters on the diffraction characteristics of typical single and multiple pit systems.

The Diffraction of Multidirectional Random Waves by Rectangular Submarine Pits

2002 ◽  
Author(s):  
Hong Sik Lee ◽  
A. Neil Williams
Keyword(s):  
Boundary Integral ◽  
Integral Approach ◽  
Two Dimensional ◽  
Regular Wave ◽  
Random Waves ◽  
Shallow Water Theory ◽  
Discrete Form ◽  
Random Surface ◽  
Directional Spectrum ◽  
Dimensional Boundary

The diffraction of multidirectional random surface waves with one or more rectangular submarine pits is investigated theoretically. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The numerical model involves the superposition of regular-wave diffraction solutions based on linearized shallow water theory obtained by a two-dimensional boundary integral approach for water of uniform depth. Numerical results are presented for multi-directional random waves that illustrate the effect of the various wave and pit parameters on the diffraction characteristics of typical single and multiple pit systems.

A three-dimensional magnetostatics computer code for insertion devices

1998 ◽  
Vol 5 (3) ◽  
pp. 481-484 ◽  
Author(s):  
Oleg Chubar ◽  
Pascal Elleaume ◽  
Joel Chavanne
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Object Oriented ◽  
Computer Code ◽  
Boundary Integral ◽  
Integral Approach ◽  
Registered Trademark ◽  
Cpu Time ◽  
Analytical Formulae ◽  
Field Integral

RADIA is a three-dimensional magnetostatics computer code optimized for the design of undulators and wigglers. It solves boundary magnetostatics problems with magnetized and current-carrying volumes using the boundary integral approach. The magnetized volumes can be arbitrary polyhedrons with non-linear (iron) or linear anisotropic (permanent magnet) characteristics. The current-carrying elements can be straight or curved blocks with rectangular cross sections. Boundary conditions are simulated by the technique of mirroring. Analytical formulae used for the computation of the field produced by a magnetized volume of a polyhedron shape are detailed. The RADIA code is written in object-oriented C++ and interfaced to Mathematica [Mathematica is a registered trademark of Wolfram Research, Inc.]. The code outperforms currently available finite-element packages with respect to the CPU time of the solver and accuracy of the field integral estimations. An application of the code to the case of a wedge-pole undulator is presented.

Boundary Element Crystal Plasticity Method

2017 ◽  
Vol 08 (03n04) ◽  
pp. 1740003
Author(s):  
Ivano Benedetti ◽  
Vincenzo Gulizzi ◽  
Vincenzo Mallardo
Keyword(s):  
Grain Boundary ◽  
Boundary Element ◽  
Crystal Plasticity ◽  
Boundary Integral Equations ◽  
Voronoi Tessellation ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Integral Approach ◽  
Rate Dependent ◽  
Individual Grains

A three-dimensional (3D) boundary element method for small strains crystal plasticity is described. The method, developed for polycrystalline aggregates, makes use of a set of boundary integral equations for modeling the individual grains, which are represented as anisotropic elasto-plastic domains. Crystal plasticity is modeled using an initial strains boundary integral approach. The integration of strongly singular volume integrals in the anisotropic elasto-plastic grain-boundary equations are discussed. Voronoi-tessellation micro-morphologies are discretized using nonstructured boundary and volume meshes. A grain-boundary incremental/iterative algorithm, with rate-dependent flow and hardening rules, is developed and discussed. The method has been assessed through several numerical simulations, which confirm robustness and accuracy.

scholarly journals Ultimate Fast Gyrosynchrotron Codes

2021 ◽  
Vol 922 (2) ◽  
pp. 103
Author(s):  
Alexey A. Kuznetsov ◽  
Gregory D. Fleishman
Keyword(s):  
Distribution Function ◽  
Pitch Angle ◽  
Three Dimensional ◽  
Computation Time ◽  
Single Spectrum ◽  
Practical Applications ◽  
Three Dimensional Modeling ◽  
Analytical Functions ◽  
Astrophysical Objects ◽  
Gyrosynchrotron Emission

Abstract The past decade has seen a dramatic increase in practical applications of microwave gyrosynchrotron emission for plasma diagnostics and three-dimensional modeling of solar flares and other astrophysical objects. This breakthrough became possible due to an apparently minor, technical development of fast gyrosynchrotron codes, which enormously reduced the computation time needed to calculate a single spectrum, while preserving the accuracy of the computation. However, the available fast codes are limited in that they can only be used for a factorized distribution over the energy and pitch angle, while the distribution of electrons over energy or pitch angle is limited to a number of predefined analytical functions. In realistic simulations, these assumptions do not hold; thus, the codes free from the mentioned limitations are called for. To remedy this situation, we extended our fast codes to work with an arbitrary input distribution function of radiating electrons. We accomplished this by implementing fast codes for a distribution function described by an arbitrary numerically defined array. In addition, we removed several other limitations of the available fast codes and improved treatment of the free–free component. The ultimate fast codes presented here allow for an arbitrary combination of the analytically and numerically defined distributions, which offers the most flexible use of the fast codes. We illustrate the code with a few simple examples.

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