Título:	Exploring turbulent wakes in a non-uniformly stratified environment for submarine detection
Autor(es):	Nadaf, Elias de Castro
Orientador(es):	Radko, Timour Brown, Justin M.
Palavras-chave:	Wake dynamics Stratification Submarine detection
Áreas de conhecimento da DGPM:	Oceanografia física
Data do documento:	2022
Editor:	Naval Postgraduate School (NPS), Monterey, EUA
Descrição:	This study aims to explore the behavior of turbulent wakes generated by a spherical submerged body propagating with constant speed in a non-uniformly stratified fluid. The investigation is based on a series of high-resolution numerical simulations in which the background stratification is systematically varied. We consider one linear and five non-linear temperature profiles and two sets of Froude numbers (Fr), Fr = 1.0 and Fr = 3.2. The analysis of dissipation of thermal variance (χ) shows that the shape of the wake for non-uniform profiles is more horizontally spread, and internal waves are much stronger than in linear stratification. Experiments with Fr = 1.0 show a rather asymmetric energy distribution caused by internal wave reflections from low-gradient regions. An idealized model demonstrates that internal waves emitted at horizontal angles shallower than roughly 64 degrees are reflected. For Fr = 3.2, internal waves are radiated at steeper angles and transmitted more. Using decay rates of χ, the maximum detection time of the wake can be estimated, showing that for Fr = 3.2, the thermal signal lasts four to five times longer than for Fr = 1.0. Furthermore, concave profiles produce signals lasting approximately twice as long as those for linear profiles, whereas low-gradient types have half the duration. This research is expected to assist in the development of non-traditional detection algorithms for undersea warfare.
Tipo de Acesso:	Acesso aberto
URI:	https://www.repositorio.mar.mil.br/handle/ripcmb/846481
Tipo:	Tese
Aparece nas coleções:	Hidrografia e Navegação: Coleção de Teses

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