Chapman, C. J. Caustics in cylindrical ducts. (English) Zbl 0966.76082 Proc. R. Soc. Lond., Ser. A, Math. Phys. Eng. Sci. 455, No. 1987, 2529-2548 (1999). This paper addresses the caustic structure of the acoustic field reflected from the end face of a circular cylindrical duct when the incident field from inside the duct is a spinning acoustic mode. The rays of the reflected field are helices, which begin at the circular rim of the end face of the duct as diffracted rays. The caustics of the reflected field are infinite in number and have cusps. The paper analyzes the resulting longitudinal chain of infinitely many cusped caustics. The paper also determines the orders of the length and width of a wall region and ‘outer region’. The orders are used to construct asymptotic expansions for the position of the caustics in all the regions. Reviewer: J.E.Ffowcs Williams (Cambridge) Cited in 3 Documents MSC: 76Q05 Hydro- and aero-acoustics Keywords:caustic position; acoustic field; circular cylindrical duct; incident field; spinning acoustic mode; reflected field; asymptotic expansions PDFBibTeX XMLCite \textit{C. J. Chapman}, Proc. R. Soc. Lond., Ser. A, Math. Phys. Eng. Sci. 455, No. 1987, 2529--2548 (1999; Zbl 0966.76082) Full Text: DOI Digital Library of Mathematical Functions: §36.14(iv) Acoustics ‣ §36.14 Other Physical Applications ‣ Applications ‣ Chapter 36 Integrals with Coalescing Saddles