TRANSACTIONS OF THE KRYLOV STATE RESEARCH CENTRE

Science journal

 
ISSN (print) 2542-2324 /(online) 2618-8244


Articles of The Transactions of KSRC








Effect of waveguide with solid elastic bottom upon diffraction of pulse acoustic signals on perfect and elastic bodies



Full text article ( in russian)

Year

 
2018

Issue

 
384

Volume

 
2

Pages

 
105-111

Caption

 
Effect of waveguide with solid elastic bottom upon diffraction of pulse acoustic signals on perfect and elastic bodies

Authors

 
Kleschev A.

Keywords

 
scatterer, oblong spheroid, diffraction, elastic solid bottom, boundary conditions, phase speed, group velocity.

DOI

 
10.24937/2542-2324-2018-2-384-105-111

Summary

 
Object and purpose of research.This paper describes the method of imaginary sources and scatterers in application to the diffraction problem for acoustic pulse signals on analytical and non-analytical bodies (perfect and elastic) put into the waveguide not with conventional (fluid or perfect) but with solid elastic bottom.
Subject matter and methodsThe theoretical approach is based on the known method of imaginary sources to which the author added imaginary scatterers. For pulse acoustic signals, the method of normal waves is unacceptable because it relies on the phase velocity of signal propagation, and the pulses are bunches of energy, so they can only propagate with group velocity, i.e. the core notion of imaginary sources and scatterers method.
Main results.The calculations were performed for the pulses reflected from a soft spheroid put into a plane waveguide with two variants of bottom: perfectly rigid and solid elastic. It is shown that in the first case reflected pulses undergo complete internal reflection from the solid elastic bottom, so their reflection factor is 1, i.e. the same as for absolutely rigid bottom. The paper solves, through the method of integral equations, the diffraction problem for acoustic pulses on an elastic non-analytical scatterer put into a plane waveguide with solid elastic bottom. The scatterer had arbitrary position with respect to waveguide boundaries.
Conclusion.Propagation and reflection of pulse signals in plane waveguide should be studied as per the method of imaginary sources and scatterers. Solid elastic bottom can be substituted by alsolutely rigid one if the pulses of sources, falling onto elastic solid bottom, undergo complete internal reflection. The adopted model of imaginary sources and scatterers is acceptable for first reflected pulses in the waveguide with solid elastic bottom.

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ISSN (print) 2542-2324 / ISSN (online) 2618-8244

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