On the Influence of Microbubbles on the Turbulence Induced by a Surface Wave

IF 0.8 4区地球科学 Q4 ENGINEERING, ELECTRICAL & ELECTRONIC Radiophysics and Quantum Electronics Pub Date : 2023-12-13 DOI:10.1007/s11141-023-10279-3

O. A. Druzhinin

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Abstract

We use the direct numerical simulation (DNS) method to study the vortex structure of the near-surface water layer, which is saturated with air bubbles, in the presence of a stationary surface wave. A wave with a wavelength of 15 cm and a steepness of 0.2 (an amplitude of about 0.5 cm) and bubbles 400 μm in diameter (microbubbles) are considered. Complete three-dimensional fluid motion equations (Navier–Stokes equations) are solved by the DNS method simultaneously with the equations of motion of individual bubbles with allowance for their influence on the carrier flow. Under the influence of the surface wave, the flow in the near-surface layer becomes turbulent and characterized by the presence of vortex structures stretched along the wave propagation direction. To analyze the vortex structure of the flow, the instantaneous velocity gradient tensor is calculated, and its complex eigenvalues, whose imaginary part characterizes the local vorticity of the flow, are calculated, while filtering out the contribution of the purely shear component (vortex sheet). Average profiles of the eigenvalues and the fluctuations, which are obtained at the stage of the statistically stationary flow, show that the influence of the bubbles lead to intensification of small-scale vortices and turbulent pulsations in water.

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论微气泡对表面波引起的湍流的影响

我们采用直接数值模拟（DNS）方法研究了静止表面波作用下气泡饱和的近表面水层的涡旋结构。考虑的波长为 15 厘米，陡度为 0.2（振幅约为 0.5 厘米），气泡直径为 400 微米（微气泡）。采用 DNS 方法同时求解了完整的三维流体运动方程（纳维-斯托克斯方程）和单个气泡的运动方程，并考虑了气泡对载体流的影响。在表面波的影响下，近表面层的流动变得湍急，其特点是存在沿波传播方向延伸的涡旋结构。为了分析流动的涡旋结构，计算了瞬时速度梯度张量及其复特征值（其虚部表示流动的局部涡度），同时过滤掉了纯剪切分量（涡旋片）的贡献。在统计静止流阶段获得的特征值和波动的平均剖面图表明，气泡的影响会导致水中小尺度涡旋和湍流脉动的加剧。

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来源期刊

Radiophysics and Quantum Electronics ENGINEERING, ELECTRICAL & ELECTRONIC-PHYSICS, APPLIED

CiteScore

1.10

自引率

12.50%

发文量

审稿时长

6-12 weeks

期刊介绍： Radiophysics and Quantum Electronics contains the most recent and best Russian research on topics such as: Radio astronomy; Plasma astrophysics; Ionospheric, atmospheric and oceanic physics; Radiowave propagation; Quantum radiophysics; Pphysics of oscillations and waves; Physics of plasmas; Statistical radiophysics; Electrodynamics; Vacuum and plasma electronics; Acoustics; Solid-state electronics. Radiophysics and Quantum Electronics is a translation of the Russian journal Izvestiya VUZ. Radiofizika, published by the Radiophysical Research Institute and N.I. Lobachevsky State University at Nizhnii Novgorod, Russia. The Russian volume-year is published in English beginning in April. All articles are peer-reviewed.