Wave-scattering from a gently curved surface

TL;DR

This paper develops a method to resum the perturbative series for wave scattering from gently curved surfaces, resulting in a derivative expansion that improves understanding of wave-surface interactions.

Contribution

It introduces a recursive relation-based resummation technique for the scattering amplitude, extending the small-slope approximation to all orders.

Findings

Resummed series yields a derivative expansion of the scattering amplitude.

The approach relates to and extends the small-slope approximation.

Provides a potentially exact description in the quasi-specular limit.

Abstract

We study wave scattering from a gently curved surface. We show that the recursive relations, implied by shift invariance, among the coefficients of the perturbative series for the scattering amplitude allow to perform an infinite resummation of the perturbative series to all orders in the amplitude of the corrugation. The resummed series provides a derivative expansion of the scattering amplitude in powers of derivatives of the height profile, which is expected to become exact in the limit of quasi-specular scattering. We discuss the relation of our results with the so-called small-slope approximation introduced some time ago by Voronovich.