Evaluation of oscillating grids and orbital shakers as means to generate isotropic and homogeneous small-scale turbulence in laboratory enclosures commonly used in plankton studies
Evaluation of oscillating grids and orbital shakers as means to generate isotropic and homogeneous small-scale turbulence in laboratory enclosures commonly used in plankton studies
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DOI：
10.4319/lom.2009.7.287
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发表时间：
2009-04-01
影响因子：
2.7
通讯作者：
Lohrmann, Atle
中科院分区：
文献类型：
--
作者：
Guadayol, Oscar;Peters, Francesc;Lohrmann, Atle
湍流运动对浮游生物的影响主要在实验室中利用能够产生受控湍流条件的装置进行研究。由于技术和后勤方面的困难，此类实验中通常不会对流体动力学进行彻底的评估。在这项研究中，我们研究了两种广泛使用的系统在实验室容器中产生各向同性、均匀和静止湍流的适用性：具有大冲程长度和相对较低振荡频率的振荡网格装置和轨道振动台。湍流动能耗散率是根据声多普勒测速仪进行的速度测量来估计的。两个系统都被证明可以在相对较宽的耗散率范围内产生各向同性条件。只要冲程长度与容器的高度相当，网格搅拌罐就会在水平和垂直方向上产生均匀的湍流。轨道振动台中的湍流并不完全均匀，因为它取决于到壁和表面的距离。经验模型是在本研究检查的范围和条件下作为计算两个系统耗散率的工具而导出的。
The effects of turbulent motion on planktonic organisms have mainly been studied in the laboratory with devices capable of generating controlled turbulent conditions. Owing to technical and logistical difficulties, thorough assessments of hydrodynamics in such experiments are not routinely made. In this study, we examined the suitability of two widely used systems to generate isotropic, homogeneous, and stationary turbulence in laboratory containers: oscillating grid devices with large stroke length and relatively low frequencies of oscillation and orbital shaker tables. Turbulent kinetic energy dissipation rates were estimated from velocity measurements made with acoustic Doppler velocimeters. Both systems were shown to generate isotropic conditions in a relatively broad range of dissipation rates. Grid-stirred tanks produce homogeneous turbulence in both the horizontal and vertical dimensions, as long as stroke length is comparable to the height of the container. Turbulence in orbital shakers is not completely homogeneous, as it depends on the distance to the wall and to the surface. Empirical models are derived as a tool for the calculation of dissipation rates in the two systems within the ranges and conditions examined in this study.