Despite great developments in inertial microfluidics, there is still a lack of knowledge to precisely define the particles’ behavior in the microchannels. In the present study, as a prerequisite to experimental studies, numerical simulations have been used to study the capture efficiency of target particles in the contraction–expansion microchannel, aiming to provide an estimation of the conditions at which the channel performs best. Fluid analysis based on Navier–Stokes equations is conducted using the finite element method to determine the streamlines and vortices. The highest capture efficiency for 10, 15, and 19-micron particles occurs when the center of the vortex is approximately in the middle of the wide section (at the flow rate of 0.35 ml/min). In addition to investigating the effect of particle diameter and input flow rate, the effect of channel geometry parameters (channel height and initial length of the channel) on particle trapping has also been studied. Also, to consider great interest in separating different-sized bioparticles from a sample, a three-stage platform has been designed to separate four types of bone marrow cells and evaluate the possibility of using contraction–expansion channels in this application.

尽管惯性微流体技术有了很大的发展，但仍然缺乏精确定义微通道中粒子行为的知识。在本研究中，作为实验研究的先决条件，数值模拟已被用于研究收缩-膨胀微通道中目标粒子的捕获效率，旨在提供对通道性能最佳条件的估计。基于 Navier-Stokes 方程的流体分析是使用有限元方法进行的，以确定流线和涡流。当涡流中心大约位于宽截面的中间时（流速为 0.35 ml/min），10、15 和 19 微米颗粒的捕获效率最高。除了研究粒径和输入流速的影响外，还研究了通道几何参数（通道高度和通道初始长度）对粒子捕获的影响。此外，考虑到对从样本中分离不同大小的生物颗粒的极大兴趣，设计了一个三级平台来分离四种类型的骨髓细胞，并评估在此应用中使用收缩-扩张通道的可能性。