Implementation of local, high-order accurate boundary conditions
for time-dependent acoustic scattering
Lonny L. Thompson and Dantong He and Runnong Huan
Advanced Computational Mechanics Research Laboratory
Department of Mechanical Engineering and Engineering Mechanics
Clemson University
Clemson, South Carolina 29634-0921
NCA-Vol. 27, Proceedings of the ASME Noise Control and Acoustics Division - 2000, ASME 2000, pp. 27-38;
2000 International Mechanical Engineering Congress and Exposition,
Symposium on Computational Acoustics,
Nov. 5-10, 2000, Orlando, Florida.
Abstract
A sequence of high-order accurate radiation boundary conditions
involving local differential operators of auxiliary functions
on a circular boundary are implemented in a spectral finite
element method with mixed time integration.
The semi-discrete finite element equations
are integrated explicitly in time while the
auxiliary functions on the circular boundary
are integrated using a semi-implicit time-integration method.
An efficient algorithm results which avoids the need to update
either the solutions for the field variable
or the boundary functions at intermediate time steps.
Using this mixed time integration approach, a very natural and
efficient implementation of the high-order accurate, local boundary
conditions is obtained without altering the local/sparse character of
the finite element equations.
Numerical studies of time-dependent scattering
from an elliptic object demonstrate the rapid convergence
and accuracy of the implementation.
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