Abstract
Based on the open source software 2D numerical simulations of incompressible stratified fluids flows have been performed. They are characterized by a wide range of values of internal scales that are not in a homogeneous liquid. Mathematical model is based on the fundamental set of differential equations of inhomogeneous multicomponent fluid mechanics. The problem is solved using the finite volume method in an open source package OpenFOAM. The method allows analyzing in a single formulation the dynamics and fine structure of flow patterns past obstacles in a wide range of flow parameters. A particular attention is focused at construction of a high quality computational grid which satisfies basic requirements for resolution of all the microscales of the problem in high-gradient regions of the flow. The calculations were performed in parallel regime on computational facilities of the web-laboratory UniHUB (www.unihub.ru). The same system of equations and a general numerical algorithm were used for the whole range of the parameters under consideration. The calculation results are in a qualitative agreement with the data from laboratory experiments. Transient flow patterns past obstacles are analyzed, and physical mechanisms are determined, which are responsible for formation of vortices in regions with high density gradients near the edges of an obstacle. For all the velocities of the body motion, the flow field is characterized by a complicated internal structure. In the flow pattern around motionless body dissipative gravity waves are manifested at the edges of the strip. Around the slowly moving body a group of attached waves, are formed in opposite phases at the edges of the wedge. Then, the main flow components become vortices, which are formed around the edge of the wedge and manifested downstream in the wake. With further increase in velocity of the body motion, the flow pattern becomes more non-stationary.
Highlights
Mathematical model is based on the fundamental set of differential equations of inhomogeneous multicomponent fluid mechanics
The method allows analyzing in a single formulation the dynamics and fine structure of flow patterns past obstacles in a wide range of flow parameters
Transient flow patterns past obstacles are analyzed, and physical mechanisms are determined, which are responsible for formation of vortices in regions with high density gradients near the edges of an obstacle
Summary
В настоящей работе изучаются механизмы формирования, развития, распада волновых и вихревых компонент течений в стратифицированной среде, где волны и вихри существуют одновременно и активно взаимодействуют между собой. Сложность подхода – внутренняя многомасштабность, отражающая присутствие крупных компонент течений (вихри, внутренние волны в толще жидкости) и тонких высокоградиентных прослоек, разделяющих структурно отличающиеся области течения [1]. Гравитационные (внутренние) волны являются важным элементом динамики морской среды и атмосферы, они переносят на большие расстояния энергию и импульс, интенсифицируют перенос вещества [2, 3]. Численными методами исследуется формирование тонкой структуры течений, которая влияет на перенос вещества, процессы разделения компонент течения и повышения локальной концентрации примесей. Целью работы является развитие методики численного моделирования течений непрерывно стратифицированных жидкостей с учетом геометрии препятствий, эффектов вязкости и диффузии
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