Völtz C
Experimentalphysik V, Universität Bayreuth, D-95440 Bayreuth, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Aug;68(2 Pt 1):021408. doi: 10.1103/PhysRevE.68.021408. Epub 2003 Aug 26.
The temporal evolution of the density profiles at the interface of a Rayleigh-Taylor instability in a sedimenting suspension is experimentally investigated. It is found that the sand-glycerin density gradients within the interface change with time, and that the evolution of the gradients differs significantly, depending on the location: The density profiles become steeper in the regions where the suspension flows downwards, whereas the profiles become flatter in the regions where the fluid flows upwards. This observation shows that there is a motion of the sand grains relative to the carrier fluid and hence reveals the prevailing granular dynamics in the suspension interface. It shows a behavior of the suspension which is different from the behavior of a homogeneous Newtonian one-component fluid whose density profiles do not change in time. Another interesting result is that the slopes of the profiles differ already at the very beginning (t=0) of the evolution of the instability, indicating that the suspension might have self-structured prior to instability onset.
对沉降悬浮液中瑞利 - 泰勒不稳定性界面处密度分布的时间演化进行了实验研究。研究发现，界面内的砂 - 甘油密度梯度随时间变化，并且梯度的演化根据位置有显著差异：在悬浮液向下流动的区域，密度分布变得更陡，而在流体向上流动的区域，分布变得更平坦。这一观察结果表明，砂粒相对于载液存在运动，从而揭示了悬浮液界面中占主导地位的颗粒动力学。它显示了悬浮液的一种行为，这种行为不同于均匀牛顿单组分流体的行为，后者的密度分布不会随时间变化。另一个有趣的结果是，在不稳定性演化的一开始（t = 0），分布的斜率就已经不同，这表明悬浮液在不稳定性开始之前可能已经自我结构化。
