Physical Fields of Ship and Ocean                                                                      

DOI: http://www.dx.doi.org/10.24866/2227-6858/2020-1-11

Korchaka A., Yem A., Korochencev V. 
ANATOLY KORCHAKA, Postgraduate, e-mail: anatoliy_korchaka_informbox@mail.ru, 
ARTYOM YEM, Postgraduate, e-mail: art_of_motion@mail.ru 
VLADIMIR KOROCHENTSEV, Doctor of Physics and Mathematical Sciences, Professor, 
Head of Department, ScopusID: 6603474562, e-mail: korochentsev.vi@dvfu.ru 
Department of Instrument Engineering, School of Engineering 
Far Eastern Federal University 
8 Sukhanova St., Vladivostok, Russia, 690091

Mathematical model of fish finder sonar

Abstract: One of the most important aspects of the development of fishing industry is availability and continuous improvement of up-to-date hydroacoustic means for fishing fleet. The crucial part of most hydroacoustic devices is the antenna. Analysis of its wave field is an integral part of design of any new device. All known methods of solving the aforesaid problem often require considerable computer time for calculations and do not always provide the acceptable accuracy. The purpose of this work is to develop computational algorithms as a solution for the problem of analyzing the wave field of the hydroacoustic antenna array (sonar), located within inhomogeneous physical volume – fishing zone, in the presence of biological clusters (shoals of fish). The proposed approach is based on the method of directed Green's functions, application of which reduces the performance requirements of computers used for modeling. The classical theory of acoustic wave propagation in layered media is applied in order to account for the inhomogeneities. In order to solve the problems considered herein, the said method has been used for the first time. Results have clearly demonstrated that the presented mathematical model is adequate to the purpose, on the basis of which computational algorithms are developed that enable numerical simulation of wave fields in layered environments. The efficiency of the proposed algorithms is demonstrated by the example of calculating the field of a simple three-element antenna array in marine environment, close to considerable volumes of acoustic inhomogeneities (accumulations of hydrobionts). The practical significance of the results of this work consists in the possibility of application of the developed algorithms both for educational purposes and for engineering calculations in the course of design of hydroacoustic equipment. Using the proposed approach allows to reduce the cost of computer time without significant losses in the accuracy of calculation results. 
Keywords: antennas designing, hydroacoustic antenna array, analysis of the wave field, acoustic heterogeneity, layered medium, Green's functions, reflection coefficient. 

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