A Theory for Electromagnetic Radiation and Coupling

This is latest version of my theory. I have (1)revised the abstract and the Introduction section; (2) added a section for mutual coupling to show that EM radiation and EM mutual coupling are almost the same issue, including figures for mutual couplings, and detailed expressions for the mutual coupling energies; (3)added the real radiative power for the Hertzian dipole; (4) added example of a Yagi antenna; (5) added some detailed parameters for numerical implementation.

Optimization and software-numerical implementation of miller's algorithm on a four-frequency model of solid vibration movement

On the basis of a programmed-numerical approach, new values of the coefficients in the Miller orientation algorithm are obtained. For this, an analytical reference model of the angular motion of a rigid body was applied in the form of a four-frequency representation of the orientation quaternion.The numerical implementation of the reference model for a given set of frequencies is presented in the form of constructed trajectories in the configuration space of orientation parameters. A software-numerical implementation of Miller's algorithm is carried out for different values of the coefficients and the values of the coefficients are obtained, which optimize the error of the accumulated drift. It is shown that for the presented reference model of angular motion, Miller's algorithm with a new set of coefficients provides a lower computational drift error compared to with the classic Miller algorithm and the Ignagni modification, which are optimized for conical motion.

NUMERICAL SOLUTION OF THE PROBLEM FOR POISSON’S EQUATION WITH THE USE OF DAUBECHIES WAVELET DISCRETE-CONTINUAL FINITE ELEMENT METHOD

Numerical solution of the problem for Poisson’s equation with the use of Daubechies wavelet discrete continual finite element method (specific version of wavelet-based discrete-continual finite element method) is under consideration in the distinctive paper. The operational initial continual and discrete-continual formulations of the problem are given, several aspects of finite element approximation are considered. Some information about the numerical implementation and an example of analysis are presented.

Parametric and V&V study in a fundamental CFD process: revisiting the lid-driven cavity flow

Purpose The openings on aircraft structures can be modeled from an aerodynamical point of view as lid-driven cavities (LDC). This paper aims to show the primary verification and validation (V&V) process in computational fluid dynamics (CFD, and to investigate the influences of numerical settings on the efficiency and accuracy for solving the LDC problem. Design/methodology/approach To dig into the details of CFD approaches, this paper outlines the design, implementation, V&V and results of an efficient explicit algorithm. The parametric study is performed thoroughly focusing on various iteration methods, grid density discretization terms and Reynolds number effects. Findings This study parameterized the numerical implementation which provides empirical insights into how computational accuracy and efficiency are affected by changing numerical settings. At a low Reynolds number (not over 1,000), the time-derivative preconditioning is necessary, and k = 0.1 can be the optimal value to guarantee the efficiency, as well as the stability. A larger artificial viscosity (c = 1/16) would relieve the calculating oscillation issue but proportionally increase the discretization error. Furthermore, the iteration method and the mesh quality are two key factors that affect the convergence efficiency, thus need to be selected “wisely”. Practical implications The study shows how numerical implementation can enhance an accurate and efficient solution. This workflow can be used to determine the best parameter settings whenever CFD researchers applying this LDC problem as a complementary design tool for testing newly developed solvers. Originality/value The studied LDC problem is representative of CFD analysis in real aircraft structures. These numerical simulations provide a cost-effective and convenient tool to understand the parameter sensitivity, solution receptivity and physics of the CFD process.

Computational studies of hydrotoparaffin plugs in wells

In Western Siberia and the Far North, complications caused by paraffin plugs in wells are not temporary. They are caused by ongoing factors, such as permafrost zones, a sharp temperature drop along the well, the high gas factor and water in the well products. The paper studies the possibility of using a high-frequency electromagnetic field to remove paraffin plugs inside the well. Mathematical modeling of the problem using a system of heat and mass transfer equations and boundary and initial conditions is described. The phase transition (melting of hydratoparaffin) is denoted by Stefan’s condition which is one of the boundary conditions. The problem does not have an analytical solution, so the numerical implementation of the solution is carried out. Graphs of dependences of melting limits on generator power, and distribution of temperature fields in wells are constructed.

Mathematical modeling of the pollutant distribution process in the Gelendzhik Bay

Currently, the pollution problem of coastal sea waters in the resort areas of the Black Sea is becoming increasingly urgent. Thousands of chemicals, industrial and household waste enter the water basins every year, which significantly worsens the state of marine waters. Storm drains are saturated with pollutants at precipitation, washing out various chemical compounds, garbage and transporting them to the sea. In addition, a separate problem is poorly self-cleaning of the Gelendzhik Bay. A complete water change occurs in the period from 1 to 6 days. This paper covers the development, research and numerical implementation of a mathematical model of the pollution transport, including petroleum products, in the Gelendzhik Bay taking into account a number of important hydrodynamic and hydrophysical factors, methods of its numerical implementation, which allow predictive modeling of the pollution spread in shallow water systems in a limited time. A hydrobiological model of a coastal system characterized by significant depth differences has been developed. A three-dimensional mathematical model is designed to research the transformation of the phosphorus, nitrogen and silicon forms in the plankton dynamics problem. It takes into account the convective and diffusive transports, absorption and release of nutrients by phytoplankton, salinity, temperature, oxygen regime, etc. Using a spatial-three-dimensional hydrodynamics model, taking into account the physical properties of water environment of the coastal system, calculation results are used as input data for the development of scenarios for the dynamics of transport processes and the transformation of pollution biogenic elements in the water.

Global electromagnetic turbulence simulations of W7-X-like plasmas with GENE-3D

The GENE-3D code, the global stellarator version of the established GENE framework, has been extended to an electromagnetic gyrokinetic code. This paper outlines the basic structure of the algorithm, highlighting the treatment of the electromagnetic terms. The numerical implementation is verified against the radially global GENE code in linear and nonlinear tokamak simulations, recovering excellent agreement between both codes. As a first application to stellarator plasmas, linear and nonlinear global simulations with kinetic electrons of ion temperature gradient (ITG) turbulence in Wendelstein 7-X were performed, showing a decrease of ITG activity through the introduction of electromagnetic effects via a finite plasma- $\beta$ . The upgrade makes it possible to study a large variety of new physical scenarios, including kinetic electron and electromagnetic effects, reducing the gap between gyrokinetic models and physically realistic systems.