Eng. Mech. Discipline, Open Univ., Milton Keynes MK7 6AA, England
At large ranges or at higher frequencies, it is necessary to incorporate a large number of isovelocity layers to achieve tolerable accuracy in fast field calculations. This has a predictable effect on computation time. There is a standard solution in terms of Airy functions that allows for a linear gradient within each layer. This paper presents a preliminary investigation of an alternative form of solution that involves Hankel functions of complex order. These arise from a transformation of the depth-separated wave equation into a form of Bessel's differential equation. Results have been obtained for a low-frequency case and are compared with results from the standard form in terms of Airy functions.