Microfluidic-based sorting systems are an integral part of many biological applications, where sorting of cells, microorganisms, and particles is of interest. In this paper, a computational fluid dynamics model is established to expand investigations on a hybrid microparticle sorting method, which combines inertia-magnetic focusing and hydrodynamic separation, known as multiplex inertia-magnetic fractionation (MIMF). This microfluidic device consists of two regions, i.e. a narrow microchannel with a magnet on its side for inertial and magnetophoretic focusing of particles and a downstream wide hydrodynamic expansion zone for particles’ separation and imaging. A Lagrangian–Eulerian framework was adopted to simulate particle trajectories using the ANSYS-Fluent discrete phase modeling (DPM) approach. Acting forces that were considered to predict particle trajectories included the drag, inertial lift, Saffman lift, gravitational, and magnetophoretic forces. User-defined functions were used for inertial lift and magnetophoretic forces that are not built-in relations in the ANSYS-Fluent DPM. Numerical results were verified and validated against the experimental data for MIMF of 5 and 11 µm magnetic particles at flow rates of 0.5–5 mL/h. Particles fractionation throughput and purity in the expansion region could be predicted with errors of 6% and 2%, respectfully. The validated model was then used to perform a numerical parametric study on the unknown effects of magnetization, particle size, higher flow rates, and fluid viscosity on MIMF. The presented numerical approach can be used as a tool for future experimental design of inertia-magnetophoretic microfluidic particle sorting devices.

基于微流体的分选系统是许多生物学应用中不可或缺的部分，其中对细胞，微生物和颗粒的分选很感兴趣。在本文中，建立了计算流体动力学模型以扩展对混合微粒分类方法的研究，该方法将惯性磁性聚焦和流体动力分离相结合，称为多重惯性磁性分离（MIMF）。该微流体装置包括两个区域，即一个狭窄的微通道，在其侧面上有一个磁体，用于对颗粒进行惯性和磁致聚焦；以及一个下游的宽流体动力学膨胀区，用于分离和成像。拉格朗日-欧拉框架采用ANSYS-Fluent离散相建模（DPM）方法来模拟粒子轨迹。被认为可以预测粒子轨迹的作用力包括阻力，惯性升力，萨夫曼升力，重力力和磁致力。用户定义的函数用于惯性升力和磁热力，这不是ANSYS-Fluent DPM中的内置关系。根据流速为0.5-5 mL / h的5和11 µm磁性颗粒的MIMF的实验数据，对数值结果进行了验证和验证。可以分别预测膨胀区域中的颗粒分馏通量和纯度，其误差分别为6％和2％。然后使用经过验证的模型对MIMF的磁化，粒径，较高流速和流体粘度的未知影响进行数值参数研究。