2025_programme: Space-time ray tracing and applications to ‘vertical modes and horizontal rays’ method

• Day: June 16, Monday
    Location / Time: C. THALIA at 11:20-11:40
• Last minutes changes: Cancelled
• Session: 09. Modeling techniques for underwater acoustic scattering and propagation (including 3D effects)
  Organiser(s): Boris Katsnelson, Pavel S. Petrov
  Chairperson(s): Boris Katsnelson, Sven Ivansson, Pavel Petrov
• Lecture: Space-time ray tracing and applications to ‘vertical modes and horizontal rays’ method
  Paper ID: 2174
  Author(s): Aleksandr Kaplun, Boris Katsnelson
  Presenter: Aleksandr Kaplun
  Abstract: In underwater acoustics problems, where dependence on horizontal coordinates arises and it is necessary to solve a 3D problem of propagation, a well known method is the expansion of the sound field into "vertical modes" and finding modal amplitudes, in particular, in a 2D ray approximation (horizontal rays). A specific feature of this approach is the frequency dependence of waveguide modes, which leads to the propagation of horizontal rays in an effective dispersive medium. In this case, to describe the propagation of signals, including broadband ones, the development of the theory of space-time horizontal rays and the corresponding methods for their construction seems adequate.\nIn this work we consider the extension of the standard ray tracing techniques which are usually used to describe Gaussian beams propagation, to the space-time case. It takes into account non-trivial dependence of different modes propagation on the frequency of signal (frequency dispersion). Such effects can be neglected in case of monochromatic signals but consideration of frequency-modulated signals forces us to use large amounts of non-optimal Fourier transforms. New approach allows us to describe propagation of such signals with their different parameters (such as phase and amplitude fronts, observable frequency and amplitude modulation, etc.) without integration through some frequency domains.\nThe corresponding eikonal equation and Hamilton’s equations are obtained and presented in the form, which allows us to solve different model problems and to find characteristics of propagating pulses in experimental situations.\nWork was supported by ISF grant 946/20 and the Ministry of Aliyah and Immigrant Absorption of Israel.\n
• Corresponding author: Dr Aleksandr Kaplun
  Affiliation: University of Haifa
  Country: Israel