In this study, a reduced-order model for a deformable particle is introduced and implemented in the framework of discrete element method (DEM) with the application in biological cells such as red blood cell (RBC). In this model, a single deformable particle comprises a clump of rigid constituent spheres whose centroids are interconnected utilizing mathematical elastic bonds. To preserve the deformability, the bond model is calibrated for the static and dynamic behaviour of an RBC by using the experimental data from the literature. Good accuracy is observed in reproducing the mechanical response of various types of RBCs under different static loadings. For the dynamic calibration, the viscoelastic behaviour and the time-dependent deformation of the RBC are investigated and exhibit a good agreement with the literature. Then, the model is coupled with the immersed boundary method to evaluate the flow characteristics of a single RBC in blood plasma. The results reveal a consistent trend in predicting the drag force on the RBC with the previous investigations. This coupled model can be used in the resolved CFD–DEM simulation of biological flows in microfluidics.

中文翻译：

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可变形颗粒的降阶模型及其在生物微流体中的应用

在这项研究中，引入了可变形颗粒的降阶模型，并在离散元素方法（DEM）的框架中实现了该模型，并将其应用于生物细胞（如红细胞（RBC））中。在此模型中，单个可变形粒子包括一团刚性组成的球体，其质心通过数学弹性键相互连接。为了保持可变形性，通过使用文献中的实验数据，针对RBC的静态和动态行为对粘结模型进行了校准。在不同静态载荷下再现各种类型的RBC的机械响应时，观察到了良好的精度。对于动态校准，研究了RBC的粘弹性行为和随时间变化的变形，并与文献有很好的一致性。然后，该模型与沉浸边界方法相结合，以评估单个RBC在血浆中的流动特性。结果揭示了与以前的研究相一致的预测红细胞阻力的趋势。该耦合模型可用于微流体中生物流的解析CFD-DEM模拟。