Experimental investigation of viscoplastic free-surface flows in a steady uniform regime
Experimental investigation of viscoplastic free-surface flows in a steady uniform regime
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稳定均匀状态下粘塑性自由表面流的实验研究
DOI：
10.1017/jfm.2014.378
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发表时间：
2014
影响因子：
3.7
通讯作者：
M. Naaim
中科院分区：
文献类型：
--
作者：
G. Chambon;A. Ghemmour;M. Naaim
摘要本文介绍了粘塑性流体自由表面流动的水力特性的实验结果。其目的是探讨预测的基础上，传统的流变表征的流体的宏观流动特性的可能性。实验是在一个倾斜的走廊带通道，使我们能够产生重力驱动的浪涌保持在实验室框架固定。研究了两种不同类型的材料：高岭土浆料和Carbopol微凝胶。在不同的实验条件（倾角，流变参数）的均匀区中测量的全球高度-速度关系和局部速度分布。然后将这些数据与基于Herschel-Bulkley本构关系和流变参数的独立测量的理论预测进行比较。非常小心一直致力于确定实验的不确定性，包括那些与流变特性。对于高岭土，实验结果与理论预测吻合得很好。与Carbopol相反，观察到测量和理论流动高度之间的系统差异。然而，速度分布仍然保持一致的赫歇尔-Bulkley流变学，我们表明，所有的实验数据可以解释为增加的流变参数（屈服应力和一致性）的10- 20%相比，在流变仪中测量的值。这种差异的潜在解释进行了讨论。
Abstract We present experimental results focused on the hydraulic properties of free-surface flows of viscoplastic fluids. The objective is to investigate the possibility of predicting macroscopic flow properties on the base of conventional rheometrical characterization of the fluids. The experiments are performed in an inclined conveyor-belt channel allowing us to generate gravity-driven surges which remain stationary in the laboratory frame. Two different types of materials are studied: Kaolin slurries and Carbopol microgels. Global height–velocity relationships and local velocity profiles are measured in the uniform zone for different experimental conditions (slope angle, rheological parameters). These data are then compared to theoretical predictions based on the Herschel–Bulkley constitutive law and independent measurements of the rheological parameters. Great care has been devoted to the determination of experimental uncertainties, including those associated with the rheometrical characterization. For Kaolin, the experimental results show excellent agreement with theoretical predictions. With Carbopol, on the contrary, a systematic discrepancy between measured and theoretical flow heights is observed. The velocity profiles do nevertheless remain consistent with a Herschel–Bulkley rheology, and we show that all experimental data can be explained by increasing the rheological parameters (yield stress and consistency) by 10–20 % compared to the values measured in the rheometer. Potential interpretations for this discrepancy are discussed.