Commun. Comput. Phys., 8 (2010), pp. 758-796.


Gaussian Beam Summation for Diffraction in Inhomogeneous Media Based on the Grid Based Particle Method

Shingyu Leung 1*, Hongkai Zhao 2

1 Department of Mathematics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
2 Department of Mathematics, University of California at Irvine, Irvine, CA 92697-3875, USA.

Received 19 August 2009; Accepted (in revised version) 9 February 2010
Available online 17 May 2010
doi:10.4208/cicp.190809.090210a

Abstract

We develop an efficient numerical method to compute single slit or double slit diffraction patterns from high frequency wave in inhomogeneous media. We approximate the high frequency asymptotic solution to the Helmholtz equation using the Eulerian Gaussian beam summation proposed in [20, 21]. The emitted rays from a slit are embedded in the phase space using an open segment. The evolution of this open curve is accurately computed using the recently developed Grid Based Particle Method [24] which results in a very efficient computational algorithm. Following the grid based particle method we proposed in [23, 24], we represent the open curve or the open surface by meshless Lagrangian particles sampled according to an underlying fixed Eulerian mesh. The end-points of the open curve are tracked explicitly and consistently with interior particles. To construct the overall wavefield, each of these sampling particles also carry necessary quantities that are obtained by solving advection-reaction equations. Numerical experiments show that the resulting method can model diffraction patterns in inhomogeneous media accurately, even in the occurrence of caustics.

AMS subject classifications: 34E05, 78A05, 78A45

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Key words: Dynamic interface, Gaussian beams, diffraction, high frequency asymptotic solution.

*Corresponding author.
Email: masyleung@ust.hk (S. Leung), zhao@math.uci.edu (H. Zhao)
 

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