Nonaka Yuki, Kikuchi Kenji, Numayama-Tsuruta Keiko, Kage Azusa, Ueno Hironori, Ishikawa Takuji
Graduate School of Biomedical Engineering, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
Dept. Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
Biol Open. 2016 Jan 19;5(2):154-60. doi: 10.1242/bio.015669.
Swimming microalgae show various taxes, such as phototaxis and gravitaxis, which sometimes result in the formation of a cell-rich layer or a patch in a suspension. Despite intensive studies on the effects of shear flow and turbulence on the inhomogeneous distribution of microalgae, the effect of a bubble plume has remained unclear. In this study, we used Chlamydomonas as model microalgae, and investigated the spatial distribution of cells in a cylindrical container with a bubble plume. The results illustrate that cells become inhomogeneously distributed in the suspension due to their motility and photo-responses. A vortical ring distribution was observed below the free surface when the bubble flow rate was sufficiently small. We performed a scaling analysis on the length scale of the vortical ring, which captured the main features of the experimental results. These findings are important in understanding transport phenomena in a microalgae suspension with a bubble plume.
游动的微藻表现出各种趋性，如趋光性和趋地性，这有时会导致在悬浮液中形成富含细胞的层或斑块。尽管对剪切流和湍流对微藻不均匀分布的影响进行了深入研究，但气泡羽流的影响仍不清楚。在本研究中，我们使用衣藻作为模型微藻，并研究了带有气泡羽流的圆柱形容器中细胞的空间分布。结果表明，由于细胞的运动性和光反应，它们在悬浮液中分布不均匀。当气泡流速足够小时，在自由表面下方观察到涡环分布。我们对涡环的长度尺度进行了标度分析，该分析捕捉到了实验结果的主要特征。这些发现对于理解带有气泡羽流的微藻悬浮液中的输运现象很重要。
