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Turbulence-plankton interactions: a new cartoon

机译：湍流与浮游生物的相互作用：一部新动画片

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摘要

Climate change redistributes turbulence in both space and time, adding urgency to understanding of turbulence effects. Many analytic and analog models used to simulate and assess effects of turbulence on plankton rely on simple Couette flow. There shear rates are constant and spatially uniform, and hence so is vorticity. Over the last decade, however, turbulence research within fluid dynamics has focused on the structure of dissipative vortices in space and time. Vorticity gradients, finite net diffusion of vorticity and small radii of curvature of streamlines are ubiquitous features of turbulent vortices at dissipation scales but are explicitly excluded from simple, steady Couette flows. All of these flow components contribute instabilities that cause rotation of particles and so are important to simulate in future laboratory devices designed to assess effects of turbulence on nutrient uptake, particle coagulation, motility and predator-prey encounter in the plankton. The Burgers vortex retains these signature features of turbulence and provides a simplified "cartoon" of vortex structure and dynamics that nevertheless obeys the Navier-Stokes equations. Moreover, this idealization closely resembles many dissipative vortices observed in both the laboratory and the field as well as in direct numerical simulations of turbulence. It is simple enough to allow both simulation in numerical models and fabrication of analog devices that selectively reproduce its features. Exercise of such numerical and analog models promises additional insights into mechanisms of turbulence effects on passive trajectories and local accumulations of both living and nonliving particles, into solute exchange with living and nonliving particles and into more subtle influences on sensory processes and swimming trajectories of plankton, including demersal organisms and settling larvae in turbulent bottom boundary layers. The literature on biological consequences of vortical turbulence has focused primarily on the smallest, Kolmogorov-scale vortices of length scale η. Theoretical dissipation spectra and direct numerical simulation, however, indicate that typical dissipative vortices with radii of 7η to 8η, peak azimuthal speeds of order 1 cm s~(-1) and lifetimes of order 10 s or longer (and much longer for moderate pelagic turbulence intensities) deserve new attention in studies of biological effects of turbulence.
机译：气候变化在时空上重新分配了湍流，增加了对湍流影响的理解的紧迫性。许多用于模拟和评估湍流对浮游生物的影响的解析模型和模拟模型都依赖于简单的Couette流。那里的剪切速率是恒定的并且在空间上是均匀的，因此涡旋也是如此。然而，在过去的十年中，流体动力学中的湍流研究集中在时空上的耗散涡旋结构上。涡度梯度，涡度的有限净扩散和流线的小曲率半径是耗散尺度下湍流涡旋的普遍特征，但明确地排除在简单，稳定的库埃特流中。所有这些流动成分都导致不稳定性，从而导致粒子旋转，因此对于在未来的实验室设备中进行仿真非常重要，该设备旨在评估湍流对浮游生物对养分吸收，粒子凝结，运动性和捕食者与猎物的接触的影响。 Burgers涡流保留了湍流的这些特征，并提供了服从Navier-Stokes方程的涡流结构和动力学的简化“卡通”。而且，这种理想化非常类似于在实验室和现场以及在湍流的直接数值模拟中观察到的许多耗散涡旋。它非常简单，既可以在数值模型中进行仿真，又可以制造选择性地重现其特征的模拟设备。运用这种数值模型和模拟模型可以进一步了解湍流对被动轨迹的影响机理以及生物和非生物颗粒的局部积累，可以与生物和非生物颗粒进行溶质交换，并且可以对浮游生物的感觉过程和游泳轨迹产生更细微的影响，包括水下生物和在湍流底部边界层中沉降的幼虫。关于涡旋湍流的生物学后果的文献主要集中在长度尺度为η的最小的Kolmogorov尺度涡旋上。然而，理论耗散谱和直接数值模拟表明，典型的耗散涡流的半径为7η至8η，峰值方位角速度为1 cm s〜（-1），寿命为10 s或更长时间（中上层的则更长）湍流强度）在湍流生物学效应研究中应引起新的重视。

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  • 来源
    《Marine ecology》 |2009年第2期|133-150|共18页
  • 作者

    Peter A. Jumars; John H. Trowbridge; Emmanuel Boss; Lee Karp-Boss;

  • 作者单位

    School of Marine Sciences, University of Maine, Orono, ME, USA Darling Marine Center, University of Maine, 193 Clark's Cove Road, Walpole, ME 04573, USA;

    Applied Ocean Physics & Engineering Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;

    School of Marine Sciences, University of Maine, Orono, ME, USA;

    School of Marine Sciences, University of Maine, Orono, ME, USA;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    plankton; shear; turbulence; vortex; vorticity;

    机译：浮游生物剪湍流涡流;涡度;

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