For citation:
Smaglichenko T. A. Merging of Euler’s method with trigonometric functions for accurate ray path in a two-gradient medium. Izvestiya of Saratov University. Mathematics. Mechanics. Informatics, 2026, vol. 26, iss. 2, pp. 175-186. DOI: 10.18500/1816-9791-2026-26-2-175-186, EDN: EVOAWM
Merging of Euler’s method with trigonometric functions for accurate ray path in a two-gradient medium
In this paper, an analytical solution is presented to provide an accurate trajectory of a ray propagating from the known position of the source to the receiver in a two-gradient medium. A system of two linear gradients connects two different layered media when the transition from one to the other occurs at some boundary. Within each medium, refractive indices determine the propagation of waves and, accordingly, the curved trajectories of rays. Different radii of curves make it difficult to track the ray as it propagates from the source to the receiver. Euler's method provides an exact solution for a one-gradient model. However, in the case of two gradients, the accurate solution cannot be obtained because of the underdetermined common system for ray curves and computational complexity. In this paper, a technique is described that combines Euler's method and trigonometric functions to derive direct formulas for calculating key angles responsible for the ray path in both gradient media. An exact solution overcomes the drawbacks of iterative approaches, which are subject to computational errors. The basic formula developed for two-gradient models was tested using a small set of real data by transforming it into a particular case of a one-gradient model. The independence of the evaluations is confirmed by comparing the calculated parameters with those taken from an earlier publication. The derived formulas are essential for solving problems in oil and gas exploration, geothermal exploration, and other challenges related to energetics. The solution can be extended for acoustic, optical, and other tasks.
- Minkhanov I. F., Dolgikh S. A., Varfolomeev M. A. Razrabotka neftyanykh i gazovykh mestorozhdenij [Development of oil and gas fields]. Kazan, KFU Publ., 2019. 96 p. (in Russian).
- Arctic LNG 2 (liquefied natural gas) projects of the NOVATEK company. Available at: https://www.novatek.ru/en/about/lng-projects/arctic-lng/ (accessed September 30, 2025).
- Smaglichenko T., Smaglichenko A., Sayankina M. Risk of deep drilling: Seismic velocities estimate for Skjalfandi Bay, Iceland based on selected coordinate descent. 17th International Conference on Management of Large-Scale System Development (MLSD), Moscow, Russian Federation, September 24–26, 2024, pp. 1–5. DOI: https://doi.org/10.1109/MLSD61779.2024.10739448
- Smaglichenko T., Bjarnason I., Smaglichenko A., Jacoby W. Method to find the minimum 1D linear gradient model for seismic tomography. Fundamenta Informaticae, 2016, vol. 146, iss. 2, pp. 211–217. DOI: https://doi.org/10.3233/FI-2016-1382
- Smaglichenko T. A., Smaglichenko A. V., Zelinka I., Chigarev B. Seismic attractor can assist in finding of geothermal area? International Journal of Parallel, Emergent and Distributed Systems, 2018, vol. 33, iss. 5, pp. 503–512. DOI: https://doi.org/10.1080/17445760.2017.1419349
- Avetisov G. P. Output angles of longitudinal seismic waves according to observations at Franz Josef Land stations. Geofizicheskie metody issledovanij v Arktike [Geophysical Methods of Exploration in the Arctic], 1974, vol. 9, pp. 96–101 (in Russian).
- Malinovskaya L. N. On the issue of calculating theoretical seismograms of interference oscillations. Voprosy dinamicheskoj teorii rasprostraneniya sejsmicheskikh voln [Questions of the dynamic theory of seismic wave propagation]. Leningrad, Leningrad State University Publ., 1959, vol. 3, pp. 356–378 (in Russian).
- Savarensky E. F. Ob uglakh izlucheniya sejsmicheskoj radiatsii i nekotorykh svyazannykh s etim voprosom [On the angles of seismic radiation emission and some related issues]. Proceedings of the Geophysical Institute of the USSR Academy of Sciences, vol. 15 (142). Moscow, USSR Academy of Sciences Publ., 1952. 111 p. (in Russian).
- Um J., Thurber C. A fast algorithm for two-point seismic ray tracing. Bulletin of the Seismological Society of America, 1987, vol. 77, iss. 3, pp. 972–986. DOI: https://doi.org/10.1785/BSSA0770030972
- Sun Y. Ray tracing in 3-D media by parametrized shooting. Geophysical Journal International, 1993, vol. 114, iss. 1, pp. 145–155. DOI: https://doi.org/10.1111/j.1365-246X.1993.tb01474.x
- Zhao D., Hasegawa A. P-wave tomographic imaging of the crust and upper mantle beneath the Japan islands. Journal of Geophysical Research: Solid Earth, 1993, vol. 98, iss. B3, pp. 4333–4353. DOI: https://doi.org/10.1029/92JB02295
- Gudmundsson O., Sambridge M. A regionalized upper mantle (RUM) seismic model. Journal of Geophysical Research: Solid Earth, 1998, vol. 103, iss. B4, pp. 7121–7136. DOI: https://doi.org/10.1029/97JB02488
- Sekine S., Koketsu K. Parametrized shooting of seismic rays in a spherical earth with discontinuities. Geophysical Journal International, 2001, vol. 146, iss. 2, pp. 497–503. DOI: https://doi.org/10.1046/j.1365-246x.2001.01472.x
- Antonova L. N., Matveeva N. N. Kinematics of waves in three-dimensional block-gradient media. Voprosy dinamicheskoj teorii rasprostraneniya sejsmicheskikh voln [Questions of the dynamic theory of seismic wave propagation]. Leningrad, Leningrad State University Publ., 1975, vol. 15, pp. 78–89 (in Russian).
- Gomaniuk Y. A., Stepanov P. Y. Variational ray tracing algorithms in solving kinematic seismic problems in two-dimensional media. Journal of Geophysics, 2024, vol. 1, pp. 24–32 (in Russian). DOI: https://doi.org/10.34926/geo.2024.79.16.003, EDN: QFTVIO
- Smaglichenko T. A., Smaglichenko A. V., Genkin A. L., Sayankina M. K. Simulation of the ray path in techniques for imaging of elastic medium. Journal of Information Technologies and Computing Systems, 2018, vol. 3, pp. 52–58 (in Russian). DOI: https://doi.org/10.14357/20718632180305, EDN: VCEEFO
- Hovem J. M. Ray trace modeling of underwater sound propagation. In: Beghi M. G. (ed.) Modeling and measurement methods for acoustic waves and for acoustic microdevices. InTech – Open Access Publisher, Rijeka, Croatia, 2013, pp. 573–598. DOI: https://doi.org/10.5772/55935
- Gröller E. Nonlinear ray tracing: Visualizing strange worlds. The Visual Computer, 1995, vol. 11, pp. 263–274. DOI: https://doi.org/10.1007/BF01901044
- 23 reads