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Title: A high-order time-parallel scheme for solving wave propagation problems via the direct construction of an approximate time-evolution operator

Our manuscript demonstrates a technique for efficiently solving the classical wave equation, the shallow water equations, and, more generally, equations of the form ∂u/∂t=Lu∂u/∂t=Lu, where LL is a skew-Hermitian differential operator. The idea is to explicitly construct an approximation to the time-evolution operator exp(τL)exp(τL) for a relatively large time-step ττ. Recently developed techniques for approximating oscillatory scalar functions by rational functions, and accelerated algorithms for computing functions of discretized differential operators are exploited. Principal advantages of the proposed method include: stability even for large time-steps, the possibility to parallelize in time over many characteristic wavelengths and large speed-ups over existing methods in situations where simulation over long times are required. Numerical examples involving the 2D rotating shallow water equations and the 2D wave equation in an inhomogenous medium are presented, and the method is compared to the 4th order Runge–Kutta (RK4) method and to the use of Chebyshev polynomials. The new method achieved high accuracy over long-time intervals, and with speeds that are orders of magnitude faster than both RK4 and the use of Chebyshev polynomials.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
1304700
Report Number(s):
LA-UR--14-21207
Journal ID: ISSN 0272-4979
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
IMA Journal of Numerical Analysis
Additional Journal Information:
Journal Volume: 36; Journal Issue: 2; Journal ID: ISSN 0272-4979
Publisher:
Oxford University Press/Institute of Mathematics and its Applications
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING time-stepping methods; optimal rational approximations; parallel-in-time; direct solver