Search

This paper presents a curvilinearly‐established finite‐difference time‐domain methodology for the enhanced 3D analysis of electromagnetic and acoustic propagation in generalised electromagnetic compatibility devices, junctions or bent ducts. Based on an exact multimodal decomposition and a higher‐order differencing topology, the new technique successfully treats complex systems of varying cross‐section and guarantees the consistent evaluation of their scattering parameters or resonance frequencies. To subdue the non‐separable modes at the structures' interfaces, a convergent grid approach is developed, while the tough case of abrupt excitations is also studied. Thus, the proposed algorithm attains significant accuracy and savings, as numerically verified by various practical problems.

A systematic, non‐orthogonal FDTD algorithm for the unified and fully dual construction of curvilinear PMLs in 3‐D lossy electromagnetic and advective acoustic problems, is presented in this paper. Postulating a consistent mathematical formulation, the novel methodology introduces a set of general vector parametric equations that describe wave propagation in both media and facilitate the effective treatment of the remarkably complex, arbitrarily‐aligned (non‐uniform) source or mean flow terms, particularly at low frequencies. The discretization procedure is performed via accurate higher‐order FDTD topological concepts, which along with a well‐posed variable transformation, suppress the undesired lattice dispersion and anisotropy errors. Hence, due to these additional degrees of design freedom and their optimal establishment, the new stable PMLs (split‐field or Maxwellian) accomplish a critical attenuation of the evanescent, vorticity or elastic wave families by carefully accounting for every loss mechanism. Numerical investigation reveals the superiority of the proposed technique in terms of various open‐region, waveguide and ducted‐domain simulations.

The path integral analysis has been used to examine the propagation of a Gaussian beam in two cases. First in free space and second in a space with a non‐penetrable obstacle, placed parallel to the direction of propagation. Full analytical equations have been given in both cases and results have been taken in the same spatial coordinates in order to facilitate comparisons. No numerical instabilities have been observed and the method seems to be quite tractable and easily extended in spaces with more that one obstacle.

A finite element formulation for the solution of 3D eddy current problems in terms of the electric intensity E is presented. A weak formulation, based on a Galerkin weighted residual procedure, is presented and edge elements, that impose only tangential continuity across element interfaces of the approximated field, are employed for the discretization of the problem with the finite element method. The reliability and validity of the suggested method is verified by its application to the calculation of the 3D eddy current distribution in two conducting systems.

The evaluation of eddy currents in cylindrical geometries is examined analytically by using a method, which utilises the second order magnetic vector potential. As an example the three‐dimensional problem of the calculation of eddy currents inside a long conducting cylinder excited by a saddle shaped coil is studied.

A boundary element technique is applied to an integral formulation of the electromagnetic field quantities, of the electric vector and magnetic scalar potentials for the evaluation of the propagation phenomenon in stratified media, of planar or cylindrical geometry, due to electric dipole sources. The use of the above described potentials simplify the solution procedure, because of the degrees of freedom, which can de introduced in choosing relations between the field quantities. The main goal of these relations is to make the numerical solution easier, while the Maxwell equations and the boundary conditions remain unaffected. Besides a three‐dimensional problem is treated as a two dimensional one. Results and plots of the field, are given for both cases of the geometry. The method can be used for determining the field inside the earth in geological studies, propagation in stratified media, cable technology, shielding problems e.t.c.

A method, which is using the electric vector potential T and the magnetic scalar potential Ω is presented for the calculation of the electro‐magnetic field inside conducting cylinders of infinite length.The current source is an oscillating current dipole arbitrarilly oriented. The Green's function method is used for the transformation of the Helmholtz's equations for T and Ω into integral ones. Finally a boundary element technique is used to obtain a system of simultaneous equations. In this system the number of the unknows is greater than the number of the availiable simultaneous equations.Thus some additional conditions between the field quantities, have to be added to the boundary conditions to obtain the final solution of the problem. Problems of electrical machines, electromagnetic shielding or even, problems related to human bodies can be treated with the following analysis.