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Chin. Phys. B, 2026, Vol. 35(2): 024303    DOI: 10.1088/1674-1056/ae1b7c
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS Prev   Next  

Boundary effects on modal shape in deep ocean via non-integer order parabolic cylinder functions

Jian-Kang Zhan(詹建康)1,2,3, Sheng-Chun Piao(朴胜春)1,2,3, and Li-Jia Gong(龚李佳)1,2,3,†
1 National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China;
2 Key Laboratory of Marine Information Acquisition and Security (Harbin Engineering University), Ministry of Industry and Information Technology, Harbin 150001, China;
3 College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Abstract  This study investigates the effects of ocean boundaries on modal shapes in very-low-frequency (VLF, 1-10 Hz) sound propagation through the deep ocean. Utilizing a normal mode solution formulated in terms of parabolic cylinder functions (PCF), we demonstrate that boundary interactions induce a phase change reduction below $-\pi$ at frequencies of several hertz. This reduction, in turn, forces a key transition in the solution, shifting the order of the PCF from integer to non-integer values. Analysis of the characteristic shape of the PCF versus its order reveals that these boundary-influenced modes exhibit an energy shift toward deeper regions and a weakened axial convergence of the underwater sound field.
Keywords:  very-low-frequency sound propagation      normal modes      parabolic cylinder function  
Received:  20 September 2025      Revised:  01 November 2025      Accepted manuscript online:  05 November 2025
PACS:  43.30.+m (Underwater sound)  
  43.30.-k (Underwater sound)  
Fund: Project supported by the National Natural Science Foundation of China (Grant No. 12204128).
Corresponding Authors:  Li-Jia Gong     E-mail:  lijia.gong@hrbeu.edu.cn

Cite this article: 

Jian-Kang Zhan(詹建康), Sheng-Chun Piao(朴胜春), and Li-Jia Gong(龚李佳) Boundary effects on modal shape in deep ocean via non-integer order parabolic cylinder functions 2026 Chin. Phys. B 35 024303

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