Kano T, Kinoshita S
Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Oct;76(4 Pt 2):046208. doi: 10.1103/PhysRevE.76.046208. Epub 2007 Oct 8.
The density oscillator is a simple system that exhibits self-sustained oscillation. It alternately exhibits up and down flow through a pipe which connects two containers filled with fluids of different densities. However, the mechanism of the flow reversal has not yet been fully understood. From the detailed measurements, we have found that flow reversal begins with an intrusion of fluid, which is followed by rapid growth. This process is definitely sensitive to the viscosities of the fluids, and as a consequence, the critical heights leading to flow reversal are clearly viscosity dependent. These experimental results are explained by a simple model, derived by considering forces acting on a unit volume element located at the tip of the intrusion. Using this model, we can successfully explain the mechanism of flow reversal, which is the most essential process in a density oscillator.
密度振荡器是一个展现出自激振荡的简单系统。它通过一根连接两个装有不同密度流体的容器的管道，交替呈现向上和向下的流动。然而，流动反转的机制尚未被完全理解。通过详细测量，我们发现流动反转始于流体的侵入，随后是快速增长。这个过程对流体的粘度肯定是敏感的，因此，导致流动反转的临界高度明显取决于粘度。这些实验结果由一个简单模型来解释，该模型是通过考虑作用在侵入尖端处单位体积元上的力推导出来的。利用这个模型，我们能够成功解释流动反转的机制，而流动反转是密度振荡器中最关键的过程。
