### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 5aUW6. Direct solution of the acoustic wave equation in underwater
environments with attenuation using the finite difference method.

**R. A. Zingarelli
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*Naval Res. Lab., Acoust. Simulation Sect., Stennis Space Center, MS 39529
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A finite difference solution to the acoustic wave equation for real
pressure fields which incorporates sediment attenuation has been implemented.
The differencing method is a centered space/centered time solution of the
undamped wave equation, with absorbing boundaries simulated by an offset
space/forward time solution of the radiation condition equation. This algorithm
executes efficiently on SIMD and MIMD supercomputers, and gives an acceptable
solution to the ASA ideal wedge benchmark problem. Stability, memory, and
execution time considerations will be presented. Two basic attenuation methods,
an ad hoc absorption term and a Lax solution of the damped wave equation, along
with several differencing schemes for each, were implemented. Results and
runtimes for CW and time domain benchmarks and other problems incorporating
bottom attenuation will be presented and discussed. [Work supported by ONR.]