Subscribe free to our newsletters via your
. 24/7 Space News .




TECH SPACE
An efficient method for solving sound propagation in range-dependent ocean waveguides found
by Staff Writers
Beijing, China (SPX) Apr 12, 2012


The source is located at a range of 4 km and a depth of 100 m by the: (a) analytical solution at 25 Hz; (b) present model at 25 Hz; (c) analytical solution at 100 Hz; (d) present model at 100 Hz. Credit: Science China Press.

The coupled normal mode method is a powerful approach for solving range-dependent propagation problems in underwater acoustics. An important area of study is to improve stability and efficiency so as to be able to deal with complex scenarios in a realistic environment.

Professor LUO Wenyu and his group from the State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, set out to tackle this problem. After several years of innovative research, they have developed an accurate, efficient, and numerically stable coupled normal mode method to solve the range-dependent propagation problem.

Their work, entitled "A numerically stable coupled-mode formulation for acoustic propagation in range-dependent waveguides", was published in SCIENCE CHINA Physics, Mechanics and Astronomy. 2012, Vol. 55(4).

Underwater sound propagation in range-dependent waveguides is critical to many studies and applications in the area of underwater acoustics. Neglect of waveguide range-dependence may lead to significant prediction errors. A number of approaches have been developed for solving this problem.

Despite significant recent advances, problems such as intensive computation and instability remain unsolved. Therefore, the need for developing new approaches with better efficiency, stability, and accuracy is urgent.

In the method proposed by LUO et al., the direct global matrix (DGM) approach is applied. As is well-established, the primary advantage of the DGM approach is that it gives numerically stable solutions when there is evanescence across layers, and it does this without special numerical treatment.

Therefore, the proposed method is unconditionally stable. Furthermore, by introducing appropriately normalized range solutions, the overflow problem inherent in certain existing models is eliminated. In addition, general source conditions were put forward, which significantly extends the applicability of the proposed model compared to existing models.

To validate a range-dependent model, we have the following possible methods: comparison with analytical solutions, checking energy conservation and reciprocity and inter-model comparison. The proposed method is validated by comparison with the analytical solution to an ideal wedge benchmark problem.

Here, a range-dependent problem involving a wedge-shaped waveguide with pressure-release boundaries is analyzed. Since sound propagation towards the wedge apex will be completely backscattered due to perfectly reflecting boundaries, this test problem is an ideal benchmark for a full two-way solution to the wave equation.

The comparison indicates that the proposed model is highly accurate and numerically stable (as shown in the Figure). Furthermore, this method provides high computational efficiency. The execution time for the proposed model is less than 10 % of that of the COUPLE model, which is a widely used coupled normal mode model.

Note that although an ideal waveguide problem is used to validate the proposed method, the formulation presented also applies to realistic waveguides with penetrable bottoms and/or depth-variant sound speed profiles in water.

Implementation and promotion of this work will contribute significantly to the study of underwater sound propagation.

This research was partially supported by grants from the National Natural Science Foundation of China and the Knowledge Innovation Program of Chinese Academy of Sciences. The proposed method proves to be accurate, efficient, and numerically stable.

The researchers suggest their work be extended and applied to the study of three-dimensional effects, for instance, the horizontal refraction that is present in complex environments. This will have significant impact on the study of three-dimensional underwater sound propagation.

See article: Luo W Y, Yang C M, Qin J X, et al. A numerically stable coupled-mode formulation for acoustic propagation in range-dependent waveguides. SCIENCE CHINA Physics, Mechanics and Astronomy, 2012, 55(4): 572-588

.


Related Links
Science in China Press
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








TECH SPACE
Handover of Japan-built Radar to NASA
Greenbelt, MD (SPX) Apr 04, 2012
On March 30, the Japan Aerospace Exploration Agency (JAXA) officially handed off a new satellite instrument to NASA at Goddard Space Flight Center, Greenbelt, Md. The Dual-frequency Precipitation Radar (DPR) was designed and built by JAXA and Japan's National Institute of Information and Communications Technology (NICT). The DPR is one of two instruments that will fly aboard NASA's Core Ob ... read more


TECH SPACE
Russia postpones Luna-Glob moon mission

Russia Plans to Launch Lunar Rovers to Moon after 2020

Russia to explore moon

Earth's Other Moons

TECH SPACE
Mars Express - Pit chains on the Tharsis volcanic bulge

Post Solstice Rover Takes The Opportunity For A Wiggle

Russia and Europe give boost to Mars robotic mission

Mars missions race, India takes lead

TECH SPACE
Commentary: Innovate or evaporate

United Launch Alliance Announces New Human Launch Services Organization

Private Lunar mission and the future of space tourism

Inventors limber up for Geneva showcase

TECH SPACE
China's Lunar Docking

Shenzhou-9 may take female astronaut to space

China to launch 100 satellites during 2011-15

Three for Tiangong

TECH SPACE
Learn to dock ATV the astronaut way

Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

Busy first days for ATV Edoardo Amaldi

Space Savings for ISS Science Samples

TECH SPACE
Dragon Expected to Set Historic Course

NASA Awards Launch Contract For Goes-R And Goes-S Missions

Spy satellite-carrying rocket blasts off

Orbital Receives Order for Minotaur I Space Launch Vehicle From USAF

TECH SPACE
When Stellar Metallicity Sparks Planet Formation

Study On Extrasolar Planet Orbits Suggests That Solar System Structure Is The Norm

NASA Extends Kepler, Spitzer, Planck Missions

NASA's Kepler Mission Awarded Mission Extension

TECH SPACE
US sues Apple, publishers yield on e-book pricing

Instagram fans moan over slap in the Facebook

Sony straps on Internet-linked wristwatch

An efficient method for solving sound propagation in range-dependent ocean waveguides found




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement