Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, 630090.
Novosibirsk State University, Pirogova Street. 2, Novosibirsk, Russia, 630090.
Sci Rep. 2021 Nov 29;11(1):23085. doi: 10.1038/s41598-021-02514-6.
Looking for an optimal flow shape for culture growth in vortex bioreactors, an intriguing and impressive structure has been observed that mimics the strong swirling flows in the atmosphere (tornado) and ocean (waterspout). To better understand the flow nature and topology, this experimental study explores the development of vortex breakdown (VB) in a lab-scale swirling flow of two immiscible fluids filling a vertical cylindrical container. The rotating bottom disk drives the circulation of both fluids while the sidewall is stationary. The container can be either sealed with the still top disk (SC) or open (OC). As the rotation strength (Re) increases, a new circulation cell occurs in each fluid-the dual VB. In case SC, VB first emerges in the lower fluid at Re = 475 and then in the upper fluid at Re = 746. In case OC, VB first emerges in the upper fluid at Re = 524 and then in the lower fluid at Re = 538. The flow remains steady and axisymmetric with the interface and the free surface being just slightly deformed in the studied range of Re. Such two-VB swirling flows can provide efficient mixing in aerial or two-fluid bioreactors.
为了寻找涡旋生物反应器中培养生长的最佳流型，人们观察到一种引人入胜的、令人印象深刻的结构，它模拟了大气（龙卷风）和海洋（水龙卷）中的强旋流。为了更好地了解流场特性和拓扑结构，本实验研究探索了在填充有两种不混溶液体的立式圆柱形容器中，旋涡破裂（VB）在实验室规模的旋流中的发展。旋转的底部圆盘驱动两种流体的循环，而侧壁是静止的。容器可以用静止的顶部圆盘（SC）密封，也可以敞开（OC）。随着旋转强度（Re）的增加，在每种流体中都会出现一个新的循环单元——双 VB。在 SC 情况下，VB 首先在下部流体中于 Re=475 时出现，然后在 Re=746 时在上部流体中出现。在 OC 情况下，VB 首先在上部流体中于 Re=524 时出现，然后在 Re=538 时在下部流体中出现。在研究的 Re 范围内，流场保持稳定和轴对称，界面和自由表面只是略有变形。这种双 VB 旋流可以为气升式或两流体生物反应器提供高效混合。
