High Frequency Wave Propagation

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A Fast Phase Space Method for Computing Creeping Rays

Olof Runborg

Royal Institute of Technology, KTH

Abstract:  Creeping rays can give an important contribution to the solution of medium to high frequency scattering problems. They are generated at the shadowlines of the illuminated scatterer and propagate along geodesics on the scatterer surface, continuously shedding diffracted rays in their tangential direction. We show how the ray propagation problem can be formulated as a partial differential equation (PDE) in a three-dimensional phase space. The PDE solution give information about all possible creeping rays. Computationally the cost of solving the PDE is less than tracing all rays individually. We show numerical results and an application to monostatic radar cross section problems where creeping rays from all illumination angles must be computed.