论文标题
流体流变对电动不稳定性和随后混合现象的强大影响
Strong effect of fluid rheology on electrokinetic instability and subsequent mixing phenomena in a microfluidic T-junction
论文作者
论文摘要
这项研究详细研究了流体的流变行为如何影响微流体T型之间的电动不稳定性（EKI）现象。具有不同幂律指数（N）值不同的非牛顿幂律模型用于获得不同流变行为的流体。我们发现，随着流体流变行为从剪切厚（N> 1）变为通过牛顿（n = 1）的剪切粉状（n <1），在相同条件下EKI现象受到了显着影响。特别地，发现这种Eki现象的强度在剪切稀释的液中明显高于牛顿和剪切厚的液体。结果，与在牛顿和剪切厚的液中相比，相应的混合现象经常使用这种EKI现象实现的剪切流体也显着增强。在这项研究中提出并讨论了有关流动动力学和混合现象的详细分析。我们还采用数据驱动的动态模式分解（DMD）技术来更详细地分析流场。特别是，有关幂律指数不同值获得的相干流量结构的信息促进了对Eki诱导的混乱对流和混合现象的理解。例如，为什么混合效率在剪切的液体中高于牛顿和剪切的液体中的混合效率。此外，我们观察到，随着幂律指数的变化，这些相干结构的空间扩展和强度有很大差异，从而为基础流动动力学的某些方面提供了宝贵的见解，而其他分析则否则这些方面尚不清楚。
This study presents a detailed investigation of how the rheological behaviour of fluid could influence the electrokinetic instability (EKI) phenomenon in a microfluidic T-junction. The non-Newtonian power-law model with different values of the power-law index (n) is used to obtain fluids of different rheological behaviours. We find that as the fluid rheological behaviour changes from shear-thickening (n > 1) to shear-thinning (n < 1) via the Newtonian (n = 1) one, the EKI phenomenon is significantly influenced under the same conditions. In particular, the intensity of this EKI phenomenon is found to be significantly higher in shear-thinning fluids than in Newtonian and shear-thickening fluids. As a result, the corresponding mixing phenomenon, often achieved using this EKI phenomenon, is also notably enhanced in shear-thinning fluids compared to that achieved in Newtonian and shear-thickening fluids. A detailed analysis of both the flow dynamics and mixing phenomena in terms of streamlines, velocity fluctuations, concentration field, mixing efficiency, etc., is presented and discussed in this study. We also employ the data-driven dynamic mode decomposition (DMD) technique to analyze the flow field in more detail. In particular, the information on the coherent flow structures obtained with different values of the power-law index facilitates the understanding of both the EKI-induced chaotic convection and mixing phenomena in a better way; for instance, why the mixing efficiency is higher in shear-thinning fluids than that in Newtonian and shear-thickening fluids. Moreover, we observe that the spatial expanse and intensity of these coherent structures differ significantly as the power-law index changes, thereby providing valuable insights into certain aspects of the underlying flow dynamics that otherwise are not clearly apparent from other analyses.
