Rheology of three-phase suspensions determined via dam-break experiments
Rheology of three-phase suspensions determined via dam-break experiments
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通过破坝实验确定三相悬浮液的流变性
DOI：
10.1098/rspa.2021.0394
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Llewellin, Edward W.
中科院分区：
文献类型：
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作者：
Birnbaum, Janine;Lev, Einat;Llewellin, Edward W.
三相悬浮液，即悬浮分散的固体颗粒和气泡的液体，在自然和工业环境中都很常见。它们的流变性限制很差，特别是对于高总悬浮分数(≳0.5)。我们使用溃坝稠度计来表征(牛顿式)玉米糖浆、塑料颗粒和二氧化碳气泡悬浮液的流变性。这项研究的动机是希望了解岩浆和熔岩的流变学。我们的实验是在火山系统的尺度上进行的：它们是在非布朗、非惯性区域进行的；气泡毛细管数在统一范围内变化；气泡和颗粒的分数分别为0 ≤φGAS≤ 0.82和0 ≤φSolid≤ 0.37。我们测量了Herschel-Bulkley流变学模型的流动前沿速度和反转，作为、和毛细管数的函数。我们发现，在中低毛细管数区域，相对粘度随增加而增加的幅度比现有理论预测的更大，并且发现剪切变稀和剪切增稠效应都取决于毛细管数。我们将我们的模型应用于现有的熔岩流侵位社区代码PyFLOWGO，并预测与当前的流变学模型相比，粘度增加和速度降低，这表明现有的模型可能不能充分解释气泡在硬化熔岩中的作用。
Three-phase suspensions, of liquid that suspends dispersed solid particles and gas bubbles, are common in both natural and industrial settings. Their rheology is poorly constrained, particularly for high total suspended fractions (≳0.5). We use a dam-break consistometer to characterize the rheology of suspensions of (Newtonian) corn syrup, plastic particles and CO2bubbles. The study is motivated by a desire to understand the rheology of magma and lava. Our experiments are scaled to the volcanic system: they are conducted in the non-Brownian, non-inertial regime; bubble capillary number is varied across unity; and bubble and particle fractions are 0 ≤φgas≤ 0.82 and 0 ≤φsolid≤ 0.37, respectively. We measure flow-front velocity and invert for a Herschel–Bulkley rheology model as a function of,, and the capillary number. We find a stronger increase in relative viscosity with increasingin the low to intermediate capillary number regime than predicted by existing theory, and find both shear-thinning and shear-thickening effects, depending on the capillary number. We apply our model to the existing community code for lava flow emplacement, PyFLOWGO, and predict increased viscosity and decreased velocity compared with current rheological models, suggesting existing models may not adequately account for the role of bubbles in stiffening lavas.