Optimised multi-stream microfluidic designs for controlled extensional deformation
Optimised multi-stream microfluidic designs for controlled extensional deformation
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DOI：
10.1007/s10404-019-2295-x
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发表时间：
2019-11
影响因子：
2.8
通讯作者：
K. Zografos;S. Haward;Mónica S. A. Oliveira
中科院分区：
文献类型：
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作者：
K. Zografos;S. Haward;Mónica S. A. Oliveira
在这项研究中，我们优化了两种类型的多流配置（T型接头和流动聚焦设计），以产生一个均匀的延伸流内定义明确的区域。前者用于产生驻点流动，允许分子积累显著的应变，这已被发现对于进行拉伸研究非常有用。后者依赖于相对侧流的存在来塑造主流并产生强延伸区域，其中流体与壁相互作用的剪切效应在感兴趣区域附近被减少。在牛顿流体流动的蠕动流动条件下，在二维（2D）和三维（3D）中进行优化。它表明，与经典形状的几何形状相比，优化的设计能够产生一个明确的区域均匀的扩展。所获得的3D优化配置的操作限制进行了研究方面的Weissenberg数为恒定粘度和剪切变稀粘弹性流体。此外，对于3D优化的流动聚焦装置，在增加雷诺数和相对的侧流和主流之间的速度比的范围内的操作限制进行了研究。对于所有获得的3D优化的多流配置，我们进行实验验证，考虑牛顿流体流动。我们的研究结果显示出良好的协议与数值研究，再现所需的运动学的设计进行了优化。
In this study, we optimise two types of multi-stream configurations (a T-junction and a flow-focusing design) to generate a homogeneous extensional flow within a well-defined region. The former is used to generate a stagnation point flow allowing molecules to accumulate significant strain, which has been found very useful for performing elongational studies. The latter relies on the presence of opposing lateral streams to shape a main stream and generate a strong region of extension in which the shearing effects of fluid–wall interactions are reduced near the region of interest. The optimisations are performed in two (2D) and three dimensions (3D) under creeping flow conditions for Newtonian fluid flow. It is demonstrated that in contrast with the classical-shaped geometries, the optimised designs are able to generate a well-defined region of homogeneous extension. The operational limits of the obtained 3D optimised configurations are investigated in terms of Weissenberg number for both constant viscosity and shear-thinning viscoelastic fluids. Additionally, for the 3D optimised flow-focusing device, the operational limits are investigated in terms of increasing Reynolds number and for a range of velocity ratios between the opposing lateral streams and the main stream. For all obtained 3D optimised multi-stream configurations, we perform the experimental validation considering a Newtonian fluid flow. Our results show good agreement with the numerical study, reproducing the desired kinematics for which the designs are optimised.