Viscosity measurement from microscale convection at high pressure and temperature
Viscosity measurement from microscale convection at high pressure and temperature
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DOI：
10.1103/physrevb.101.144202
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发表时间：
2020-04
影响因子：
3.7
通讯作者：
Hannah B. Bartlett;N. Gómez-Pérez;M. Hermes;R. S. McWilliams
中科院分区：
文献类型：
--
作者：
Hannah B. Bartlett;N. Gómez-Pérez;M. Hermes;R. S. McWilliams
诱导热对流的测量已被用来研究在同时高温高压条件下的流体粘度。通过跟踪高压约束过程中激光加热熔化的样品中夹带的颗粒，对流动进行了直接观察。有限元模型证实热对流作为检测到的运动的起源，并进行了改进，以评估流体粘度。在激光加热的金刚石砧座单元中，在2- 3GPa下部分熔化的乙醇中的流动的观察结果表明，在高于平衡固化压力的室温下，粘度急剧上升，类似于先前在甲醇中所看到的。分析表明，从激光加热的流体在静压下的对流的粘度测量是一个很有前途的策略，以确定在高熔点的压力，其中高的熔融温度和小样品排除传统的粘度测量技术的应用粘度。这些数据证实了理论预测的可检测自然对流在超低瑞利数（$\mathrm{Ra}\ensuremath{\ll}1$）在一个微观系统具有足够大的温度梯度。
Measurements of induced thermal convection have been used to study fluid viscosity at simultaneous high pressure and temperature conditions. Direct observations of flow were made by tracking entrained particles in samples melted by laser heating during high-pressure confinement. Finite element models confirmed thermal convection as the origin of the detected motions, and were refined to assess the fluid viscosity. Observations of flow in ethanol partially melted in the laser-heated diamond anvil cell at 2--3 GPa point to a sharply rising viscosity at room temperature above the equilibrium solidification pressure, similar to that seen previously in methanol. The analysis shows that measurement of viscosity from convective flow in laser-heated fluids under static pressure is a promising strategy to determine viscosity at ultrahigh pressures, where high melting temperatures and small samples preclude application of traditional viscometric techniques. The data confirm theoretical predictions of detectable natural convection at ultralow Rayleigh numbers ($\mathrm{Ra}\ensuremath{\ll}1$) in a microscopic system having sufficiently large temperature gradients.