A FINITE-ELEMENT APPROACH TO THE ELECTROMAGNETIC-INTERACTION WITH ROTATING PENETRABLE CYLINDERS OF ARBITRARY CROSS-SECTION

A method to evaluate the fields excited by an obliquely incident plane wave inside and outside a rotating cylinder of arbitrary cross sectio n is presented. A differential formulation of the problem is developed with respect to the comoving reference frame of the scatterer on a cl osed circular domain including the scatterer cross section; the bounda ry conditions account for the far-field conditions through a series ex pansion of the total field on the domain contour. The results at obliq ue incidence are then particularized for normal incidence and a hybrid finite element numerical solution is presented and discussed for TM i ncidence. The present FEM approach and the related computer code are d irectly applicable to the study of rotating piecewise-homogeneous cyli nders at normal incidence, as well as metallic cylinders coated by lay ers of penetrable materials. The model presented allows a comparison o f the Galileian relativistic model with a heuristic model previously c onsidered in [1]. Through a comparison at normal incidence between the quasi-stationary and the Galileian relativistic approach we derive a method to approximately reconstruct the Doppler frequency shift in the quasi-stationary method. Far-field and near-field numerical results f or circular and arbitrary-shape (metallic or dielectric) cylinders are presented.