Kobayashi Kazuya U, Kurita Rei
Department of Physics, Tokyo Metropolitan University, 1-1 Minamioosawa, Hachioji-shi, Tokyo, 192-0397, Japan.
Sci Rep. 2017 Oct 11;7(1):12983. doi: 10.1038/s41598-017-13409-w.
The formation of a transient stagnant domain in the presence of thermal convection was previously reported near the sol-gel transition temperature of a gelatin solution. The transient stagnant domain is observed near a critical Rayleigh number where a "roll" pattern is usually stable. It is important to understand the origin of the transient stagnant domain formation since it induces a large deformation of convection patterns; the nature of the formation of the transient stagnant domain remains unclear. Here, we observe thermal convection using several different fluids and find that stagnant domain formation is ubiquitous in two component mixtures. In addition, we find that difference in viscosity between the two components is crucial for transient stagnant domain formation, more so than the concentration gradient induced by the temperature gradient.
先前有报道称，在明胶溶液的溶胶 - 凝胶转变温度附近，热对流存在时会形成一个瞬态停滞区域。在临界瑞利数附近观察到瞬态停滞区域，而在该临界瑞利数下“滚动”模式通常是稳定的。理解瞬态停滞区域形成的起源很重要，因为它会引起对流模式的大变形；然而，瞬态停滞区域形成的本质仍不清楚。在此，我们使用几种不同的流体观察热对流，发现停滞区域的形成在两组分混合物中普遍存在。此外，我们发现两种组分之间的粘度差异对于瞬态停滞区域的形成至关重要，比温度梯度引起的浓度梯度更为关键。
