Numerical enhancements and parallel GPU implementation of the TRACEO3D model

Underwater acoustic models provide a fundamental and e cient tool to parametrically investigate hypothesis and physical phenomena through varied environmental conditions of sound propagation underwater. In this sense, requirements for model predictions in a three-dimensional ocean waveguide are expected to become more relevant, and thus expected to become more accurate as the amount of available environmental information (water temperature, bottom properties, etc.) grows. However, despite the increasing performance of modern processors, models that take into account 3D propagation still have a high computational cost which often hampers the usage of such models. Thus, the work presented in this thesis investigates a solution to enhance the numerical and computational performance of the TRACEO3D Gaussian beam model, which is able to handle full three-dimensional propagation. In this context, the development of a robust method for 3D eigenrays search is addressed, which is fundamental for the calculation of a channel impulse response. A remarkable aspect of the search strategy was its ability to provide accurate values of initial eigenray launching angles, even dealing with nonlinearity induced by the complex regime propagation of ray bouncing on the boundaries. In the same way, a optimized method for pressure eld calculation is presented, that accounts for a large numbers of sensors. These numerical enhancements and optimization of the sequential version of TRACEO3D led to signi cant improvements in its performance and accuracy. Furthermore, the present work considered the development of parallel algorithms to take advantage of the GPU architecture, looking carefully to the inherent parallelism of ray tracing and the high workload of predictions for 3D propagation. The combination of numerical enhancements and parallelization aimed to achieve the highest performance of TRACEO3D. An important aspect of this research is that validation and performance assessment were carried out not only for idealized waveguides, but also for the experimental results of a tank scale experiment. The results will demonstrate that a remarkable performance was achieved without compromising accuracy. It is expected that the contributions and remarkable reduction in runtime achieved will certainly help to overcome some of the reserves in employing a 3D model for predictions of acoustic elds

Three-dimensional global scale underwater sound modeling: The T-phase wave propagation of a southern Mid-Atlantic ridge earthquake

Author Posting. © Acoustical Society of America, 2019. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 146(3), (2019): 2124-2135, doi:10.1121/1.5126010.A three-dimensional (3D) geodesic Cartesian parabolic equation model is utilized to study the propagation of low-frequency underwater sound (5 to 20 Hz), the so-called T-phase wave, triggered by a Southern Mid-Atlantic Ridge earthquake. The sound from the earthquake was recorded at 1050 km from the epicenter by the deep water hydrophones of the Comprehensive Nuclear-Test-Ban Treaty Organization network near Ascension Island. A few hours later and at 8655 km from the epicenter, the hydrophones of the Shallow Water 2006 experiment in the U.S. East coast also registered the sound. Recorded field data showed discrepancies between expected and measured arrival angles indicating the likely occurrence of horizontal sound reflection in the long waveguide journey. Numerical modeling of this T-phase wave propagation across the Atlantic Ocean with realistic physical oceanographic inputs was performed, and the results showed the importance of 3D effects induced by the Mid-Atlantic Ridge and Atlantic Islands. Future research directions, including localization of T-phase wave generation/excitation locations, are also discussed.The authors acknowledge David Bradley and Stephen Nichols for the access and support analyzing CTBTO data. The first author acknowledges the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the University of Haifa. The funding supports for the second author were from the Office of Naval Research, USA, under Grant No. N00014-17-1-2692.2020-03-3

Raytracing baseado no príncipio de Fermat

Estudo da propagação acústica 3D em meios não homogéneos. No decorrer deste trabalho foram construídos dois modelos paramétricos de raytracing, um 2D e um 3D, baseados no princípio de Fermat, que estabelece que a trajetória de um raio entre dois pontos é aquela que minimizar o tempo de trajeto. Após estabelecer as equações de Euler-Lagrange associadas ao tempo de trajeto de um raio acústico, foram deduzidos os sistemas de equações diferenciais que modelam as trajetórias de raios acústicos. Em seguida, foram efetuadas as alterações necessárias à resolução dos sistemas deduzidos, permitindo efetuar diferentes simulações. Primeiro simulações preliminares para confirmar a veracidade dos dados calculados bem como capacidades do modelo, que se seguiram de uma comparação como outro software de raytracing e simulações na presença de re flexões. Todos os testes foram satisfatórios, sendo possível concluir que as ferramentas criadas são úteis no traçado de raios a três dimensões e na presença de campos de velocidade complexos com elevados gradientes de velocidade do som

TRACEO3D Ray tracing model for underwater noise predictions

Shipping noise is the main source of underwater noise raising concern among environmental protection organizations and the scientific community. Monitoring of noise generated by shipping traffic is a difficult challenge within the context of smart systems and solutions based on acoustic modeling are being progressively adopted to overcome it. A module of sound propagation stands as a key point for the development of a smart monitoring system since it can be used for the calculation of acoustic pressure, which can be combined with estimates of the source pressure level to produce noise predictions. This paper addresses the usage of the TRACEO3D model for application in such systems; the model validity is addressed through comparisons with results from an analytical solution and from a scale tank experiment. The comparisons show that the model is able to predict accurately the reference data, while a full-field model (normal mode-based, but adiabatic) is only accurate till a certain degree. The results show that TRACEO3D is robust enough to be used efficiently for predictions of sound propagation, to be included as a part of a smart system for underwater noise predictions.Foreign Courses Program of CNPqBrazilian Nav