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This paper presents a new approach for mitigating the unphysical delay in the RANS to LES transition, often referred to as the Grey Area, which is a common issue for hybrid RANS-LES turbulence models such as Delayed-Detached Eddy Simulation (DDES). An existing methodology designed for improving the LES performance in complex flows is adapted and tested. This is based on reducing the numerical diffusion in critical areas for permitting a

The present work focuses on the study of noise generation and radiation of an infinite open three-dimensional cavity at low Mach number with laminar upstream conditions, that is of interest to understand noise generation mechanisms in wall-bounded separated flows. A particular feature of this configuration is the oscillatory mode: shear layer mode or wake mode. For the parameters considered in the present study it is seen that while in shear layer mode the flow shows a two-dimensional behaviour, in the wake mode the flow is three-dimensional, resulting in significantly different sound sources. The influence of the acoustic feedback mechanism in SL mode has also been investigated comparing the results between different momentum thickness values at the cavity inlet. This paper presents results of sound radiated by a three-dimensional infinite open cavity with aspect ratio L/D = 4 at Reynolds number based on the cavity depth of Re D = 1500 and Mach number of M = 0.15, both for shear layer (L/θ = 67) and wake (L/θ = 84) oscillation modes. To do so, Curle integral evaluated as a post-process of an incompressible solution will be used. The results are compared with the resulting Curle post-process of a two-dimensional incompressible simulation.

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В работе исследуется стохастический метод генерации искусственных трехмерных, бездивергентных, однородных и изотропных полей скорости, основанный на рандомизированном спектральном методе. Анализируются статистические и спектральные свойства турбулентных полей, построенных с помощью данного генератора. Валидационный LES расчет, использующий полученные турбулентные поля в качестве начальных условий, демонстрирует хорошее совпадение результатов с экспериментальными данными.