High-resolution direct simulation of deep water breaking waves: transition to turbulence, bubbles and droplets production
High-resolution direct simulation of deep water breaking waves: transition to turbulence, bubbles and droplets production
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DOI：
10.1017/jfm.2022.330
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发表时间：
2022-05-24
影响因子：
3.7
通讯作者：
Deike, L.
中科院分区：
文献类型：
--
作者：
Mostert, W.;Popinet, S.;Deike, L.
我们提出了求解两相纳维-斯托克斯方程的破波的高分辨率三维 (3-D) 直接数值模拟。我们研究了雷诺数（Re，相对于粘性效应的波惯性）和邦德数（Bo，毛细管长度上的波尺度）对强切入式破碎机的能量、气泡和液滴统计的作用。我们探索了高 Re 和 Bo 下的渐近状态，并与实验室碎波进行了比较。在能量上，破碎波从层流过渡到 3-D 湍流的时间尺度取决于湍流 Re，最高可达类似于 100 的极限值 Re (lambda)，与其他规范湍流中的混合过渡一致。我们描述了毛细管效应对冲击射流和摄入主腔形状以及随后的破碎过程的作用，并扩展了 Deike 等人的浮力-能量尺度。 （J. Fluid Mech.，第 801 卷，2016 年，第 91-129 页）来解释空腔形状及其与 Hinze 标度 rH 的标度分离。我们确认了气泡尺寸分布的两种状态，当 r > r(H) 时，N(r/r(H)) 与 (r/r(H))(-10/3) 成正比，当 r < rH 时，N(r/r(H))(-3/2) 与 (r/r(H))(-3/2) 成正比。气泡的分辨率比 r(H) 低一个数量级，并且与实验室破碎波相比，我们观察到数值数据的良好崩溃（Deane & Stokes, Nature, vol. 418 (6900), 2002, pp. 839-844）。我们解析高 Bo 下的液滴统计数据与最近的实验非常一致（Erinin 等人，Geophys. Res. Lett.，第 46 (14) 卷，2019，第 8244-8251 页），分布形状接近与 r(d)(-2) 成比例的 N-d(r(d))。液滴统计数据的演变似乎是由撞击过程和随后飞溅的细节控制的。我们讨论了液滴的速度分布，发现喷射速度高达波相速度的四倍，这是在破碎过程中最强烈的飞溅事件中产生的。
We present high-resolution three-dimensional (3-D) direct numerical simulations of breaking waves solving for the two-phase Navier-Stokes equations. We investigate the role of the Reynolds number (Re, wave inertia relative to viscous effects) and Bond number (Bo, wave scale over the capillary length) on the energy, bubble and droplet statistics of strong plunging breakers. We explore the asymptotic regimes at high Re and Bo, and compare with laboratory breaking waves. Energetically, the breaking wave transitions from laminar to 3-D turbulent flow on a time scale that depends on the turbulent Re up to a limiting value Re (lambda) similar to 100, consistent with the mixing transition in other canonical turbulent flows. We characterize the role of capillary effects on the impacting jet and ingested main cavity shape and subsequent fragmentation process, and extend the buoyant-energetic scaling from Deike et al. (J. Fluid Mech., vol. 801, 2016, pp. 91-129) to account for the cavity shape and its scale separation from the Hinze scale, rH. We confirm two regimes in the bubble size distribution, N(r/r(H)) proportional to (r/r(H))(-10/3) for r > r(H), and proportional to (r/r(H))(-3/2) for r < rH. Bubbles are resolved up to one order of magnitude below r(H), and we observe a good collapse of the numerical data compared to laboratory breaking waves (Deane & Stokes, Nature, vol. 418 (6900), 2002, pp. 839-844). We resolve droplet statistics at high Bo in good agreement with recent experiments (Erinin et al., Geophys. Res. Lett., vol. 46 (14), 2019, pp. 8244-8251), with a distribution shape close to N-d(r(d)) proportional to r(d)(-2). The evolution of the droplet statistics appears controlled by the details of the impact process and subsequent splash-up. We discuss velocity distributions for the droplets, finding ejection velocities up to four times the phase speed of the wave, which are produced during the most intense splashing events of the breaking process.