Fluid-structure effects of cloaking a submerged spherical shell
MetadataShow full item record
Backscattering from a cloaked submerged spherical shell is analyzed in the low, mid, and high frequency regimes. Complex poles of the scattered pressure amplitudes using Cauchy residue theory are evaluated in an effort to explain dominant features of the scattered pressure and how they are affected by the introduction of a cloak. The methodology used is similar to that performed by Sammelmann and Hackman [J. Acoust. Soc. Am. 85, 114–124 (1989); J. Acoust. Soc. Am. 89, 2096–2103 (1991); J. Acoust. Soc. Am. 90, 2705–2717 (1991)] in a series of papers written on scattering from an uncloaked spherical shell. In general, it is found that cloaking has the effect of diminishing the amplitude and shifting tonal backscatter responses. Extreme changes of normal and tangential fluid phase velocities at the fluid–solid interface when cloaking is employed leads to elimination of the “mid-frequency enhancement” near the coincidence frequency for even modestly effective cloaks, while reduction of the “high-frequency enhancement” resulting from the “thickness quasi-resonance” near the cut-off frequency of the symmetric (SB2 ) mode requires more effective cloaking, but can be practically eliminated by employing a cloak that creates tangential acoustic velocities in excess of the SB2 mode phase speed near cutoff.
The article of record as published may be found at http://dx.doi.org/10.1121/1.4816492
RightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Showing items related by title, author, creator and subject.
Song, G.; N. Buck; Agrawal, B.N. (1997);Minimizing vibrations of a exible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the rst study of pulse-width pulse-frequency modulated thruster control using command input shaping. ...
Marshall, Steven Alfred (Monterey, California. Naval Postgraduate School, 1974);A frequency-modulated radar is a radar in which a continuous-wave transmission is frequency modulated in a known manner in order to obtain range information. When the frequency modulation is linear with time, the ...
Gilliam, George N. (Monterey, CA; Naval Postgraduate School, 2021-06);Many atomic sensors depend on using a laser with a precisely defined frequency. Unfortunately, most lasers suffer from perturbations in their effective cavity length (which determines the operating frequency of the laser) ...