International audienceIn this paper, we report the numerical and experimental observations of electromagnetic or photonic jets created by a planar metallic waveguide filled with dielectric and terminated by an elliptical tip. The theoretical framework of the study is based on the wave concept iterative process (WCIP) method formulated in the spatial domain. The analyzed structure is excited by the fundamental transverse electric mode of the waveguide. The accuracy and efficiency of our program are investigated; the results of the radiated power density show a good agreement compared with those given by finite element method (FEM) simulation. The tangential electric field is computed along the elliptical tip interface and in its vicinity, i.e., in the exterior area. The parameters of the electromagnetic jet phenomenon are investigated according to the geometrical and physical characteristics of the proposed structure. Our numerical simulations are in good agreement with the measurements, indicating that the electromagnetic jet can also be obtained in the microwave field
Abstract-In this paper, Wave Concept Iterative Procedure (WCIP) is used to investigate scattering by multilayered cylindrical structures in free space and to calculate the diffracted far field by adopting a cylindrical coordinate formulation. The WCIP principle consists of alternating waves between the modal and space domains. Its iterative resolution process is always convergent in lossless media case. The proposed technique used for determining the electric far field diffracted by a multilayered cylindrical structure is validated and confronted to literature results.
In this paper, the lid driven cavity flow inside a semi-ellipse shallow cavity was simulated using the stream function vorticity approach emphasising the non-uniform grid method. Three aspect ratios of 1:4, 1:3 and 3:8 were simulated using laminar flow conditions (range of Reynolds numbers of 100-2000). Primary and secondary vortexes were monitored extensively through centre vortex location, streamlines pattern and peak stream function values. Secondary vortexes developed at Re 1500 for the aspect ratio of 1:4, whereas secondary vortexes formed at an earlier Reynolds number of 1000 for the aspect ratios of 1:3 and 3:8. The size of secondary vortexes increases as the Reynolds number increases. Similar trends can be observed in the differences between primary vortex separation angle and reattachment angle. For the entire streamline pattern, many primary vortex centre locations were situated at the right side of the cavity.
In this study, the wave concept iterative process method is developed in a spherical coordinate system in order to investigate the characteristic of multiple‐loop antennas around a multilayer sphere. The analysis method is based on the incoming and outgoing waves defined from the tangential electromagnetic fields at the interfaces of the layers. The iterative process is governed by two systems of equations linking the waves in spectral and spatial domains. The toggling between the two domains is insured by the Legendre transformation. Numerical results consider single and multiple loops (both activated and parasitic loops) around a metallic sphere coated by one or several dielectric layers. The mutual coupling and the radiation characteristic of a loop excited by two feeding sources are analysed. The influence of parasitic loops on the return loss of the activated loop is extensively investigated including the number and the position of the loops on the sphere. The coupling sensitivity between two activated feeding sources is also investigated. The presented results agree very well with the simulation and the literature.
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