Numerical and experimental studies of acoustic streaming effects on microparticles/droplets in microchannel flow
Numerical and experimental studies of acoustic streaming effects on microparticles/droplets in microchannel flow
复制标题
DOI：
10.1016/j.ijengsci.2021.103563
复制
发表时间：
2021-09-01
影响因子：
6.6
通讯作者：
Fu, Yongqing
中科院分区：
文献类型：
--
作者：
Maramizonouz, Sadaf;Rahmati, Mohammad;Fu, Yongqing
利用微流控器件的声流效应已经被证明对于生物医学工程、医学诊断设备、细胞研究和化学等许多领域中的细胞、微粒和流体操纵是重要的。声流在声流体系统中用于引导和分选微粒以及混合和泵送流体。为了理解这种声流体系统的基本物理特性，从而在实际设置中更有效地使用它们，迫切需要计算建模。虽然已经做了一些工作，数值模拟声流体系统，有很少的研究来评估不同的数值方案分析这个复杂的多物理问题的能力和精度，并直接通过实验验证。本文旨在研究声表面波引起的声流效应的微通道流动，通过使用两种不同的计算方法来模拟三维声效应。在第一种方法中，我们对振动下壁引起的整个声场进行建模。在这里，声流效应是直接计算由声场引起的密度和速度场。在第二种方法中，采用低保真度模型来捕获声流的效果，而不对声场本身进行建模。在该方法中，我们将一维衰减波的速度代入声流力公式，从而计算声流力，而不使用由声场引起的密度和速度。这两种计算方法，然后从微流实验获得的结果进行了验证。从第二种方法的结果是在合理的协议与实验，同时更有效的计算成本。相反，第一种方法虽然在计算上更昂贵，但允许估计由声波产生的压力场，从而更准确地预测微粒的动态行为。结果表明，第一种方法是最好的用于分析微流体装置中的微粒和流体操纵的机制。
Exploiting acoustic streaming effects for microfluidic devices has been proven to be important for cell, microparticle and fluid manipulation in many fields such as, biomedical engineering, medical diagnostic devices, cell studies and chemistry. Acoustic streaming is used in acoustofluidic systems for directing and sorting microparticles as well as mixing and pumping fluids. To understand the underlying physics of such acoustofluidic systems and thus use them more efficiently in practical setups, computational modelling is critically needed. Although some work has been done to numerically model acoustofluidic systems, there are few studies to evaluate the capability and accuracy of different numerical schemes for analysing this complex multi-physics problem and to be directly validated by experiments. This paper aims to investigate the acoustic streaming effects caused by surface acoustic waves in a microchannel flow by using two different computational approaches to model the acoustic effects in three dimensions. In the first approach, we model the whole acoustic field caused by the oscillating lower wall. Here, the acoustic streaming effects were directly calculated from the density and velocity fields caused by the acoustic field. In the second approach, a low fidelity model is employed to capture the effects of acoustic streaming without modelling the acoustic field itself. In this approach, we substituted the velocity of a onedimensional attenuating wave in the acoustic streaming force formula, and calculated the acoustic streaming force without using the density and velocity caused by the acoustic field. Both the computational methods are then validated by the results obtained from microflow experiments. The results from the second approach are in reasonable agreement with experiments while being more efficient in terms of computational cost. On the contrary, the first approach, while being computationally more expensive, allows to estimate the pressure field resulting from acoustic waves and thus predicts the dynamic behaviour of microparticles more accurately. Results suggest that the first approach is best to use for analysing the mechanism of microparticle and fluid manipulation in microfluidic devices.