The article presents the results of direct numerical simulation of a turbulent vortex ring with a moderate Reynolds number, interacting with the field of external turbulent fluctuations. The ring is formed by buoyancy forces from a spherically-shaped volume of elevated temperature. We consider the interaction of the ring with the field of turbulent fluctuations (of temperature and velocity) located in the form of a horizontal layer in front of the ring. The effect of separation of vortices by the sign of vorticity in a layer of fluctuations (with respect to the rotation of the ring) during the passage of the ring through this field has been found. This effect first causes the ring to slow down when the fluctuations pass outside the ring, and then to accelerate with decreasing radius when the fluctuations pass through its center. Due to buoyancy effects in the fluctuations layer, the separation of hot and cold air occurs. During the interaction with the ring, this leads to the accumulation of the reduced temperature in the core of the ring, while the increased temperature is accumulated near the axis. This temperature distribution results in a baroclinic vorticity generation leading to the reduction of the ring radius.

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涡环与背景湍流相互作用的数值研究

本文介绍了具有中等雷诺数的湍流涡环的直接数值模拟结果，该环与外部湍流波动场相互作用。所述环由来自球形体的升高温度的浮力形成。我们考虑了环与湍流场（温度和速度）之间的相互作用，该湍流场位于环前的水平层中。已经发现在环通过该场的过程中，在层的波动中（相对于环的旋转）由涡旋的符号引起的涡流分离效果。当波动通过环外时，此效果首先使环减速，然后当波动通过环的中心时，半径减小，环会加速。由于波动层中的浮力作用，发生了冷热空气的分离。在与环相互作用的过程中，这会导致降低的温度在环芯中积累，而升高的温度则在轴附近积累。该温度分布导致斜压涡度的产生，从而导致环半径的减小。