On physical optics approximation of stratified shear flows with eddy viscosity

We develop from our generalized null field method a generalization of the Kirchhoff, or physical optics, approach to diffraction theory. Corresponding to each particular null field method there is a corresponding physical optics approximation, which becomes exact when one of the coordinates being used is constant over the surface of the scattering body. We show how to improve these approximations by a computational procedure which is more efficient than those introduced in the previous paper. The reradiations from our physical optics surface sources more nearly satisfy the extinction theorem the deeper they penetrate the interiors of scattering bodies. We find that we have to introduce a new definition of the parts of a body’s surface that are directly illuminated and shadowed, and we suggest that this may be more apposite in general than the usual definition. The computational examples presented herein indicate that useful approximations to surface source densities are obtained in the umbra and penumbra of bodies. These examples also show that our scattered fields are in several particulars superior to those obtained from the conventional Kirchhoff approach. It is important to choose that physical optics approximation most appropriate for the scattering body in question.

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Modified physical optics approximation and physical theory of diffraction for RCS calculation of dielectric coated PEC

2013 IEEE Antennas and Propagation Society International Symposium (APSURSI) ◽

10.1109/aps.2013.6711606 ◽

2013 ◽

Cited By ~ 1

Author(s):

H. Mohammadzadeh ◽

A. Zeidaabadi Nezhad ◽

Z. H. Firouzeh ◽

R. Safian

Keyword(s):

Physical Theory ◽

Physical Optics ◽

Physical Optics Approximation

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Useful Solutions for Plane Wave Diffraction by Dielectric Slabs and Wedges

International Journal of Antennas and Propagation ◽

10.1155/2012/151287 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Gianluca Gennarelli ◽

Giovanni Riccio

Keyword(s):

Plane Wave ◽

Wave Diffraction ◽

Transition Function ◽

Physical Optics ◽

Surface Currents ◽

Geometrical Theory ◽

Numerical Tests ◽

Physical Optics Approximation ◽

Geometrical Theory Of Diffraction ◽

Plane Wave Diffraction

This work presents an overview of available uniform asymptotic physical optics solutions for evaluating the plane wave diffraction by some canonical geometries of large interest: dielectric slabs and wedges. Such solutions are based on a physical optics approximation of the electric and magnetic equivalent surface currents in the involved scattering integrals. The resulting diffraction coefficients are expressed in terms of the geometrical optics response of the considered structure and the standard transition function of the Uniform Geometrical Theory of Diffraction. Numerical tests and comparisons make evident the effectiveness and reliability of the presented solutions.

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