Department of Computational Mathematics, Jilin University, Changchun, Jilin 130012, China.
Department of Mechanical Engineering, National University of Singapore, Singapore 117583.
Phys Rev E. 2017 Jun;95(6-1):063314. doi: 10.1103/PhysRevE.95.063314. Epub 2017 Jun 26.
In biofluid flow systems, often the flow problems of fluids of complex structures, such as the flow of red blood cells (RBCs) through complex capillary vessels, need to be considered. The smoothed dissipative particle dynamics (SDPD), a particle-based method, is one of the easy and flexible methods to model such complex structure fluids. It couples the best features of the smoothed particle hydrodynamics (SPH) and dissipative particle dynamics (DPD), with parameters having specific physical meaning (coming from SPH discretization of the Navier-Stokes equations), combined with thermal fluctuations in a mesoscale simulation, in a similar manner to the DPD. On the other hand, the immersed boundary method (IBM), a preferred method for handling fluid-structure interaction problems, has also been widely used to handle the fluid-RBC interaction in RBC simulations. In this paper, we aim to couple SDPD and IBM together to carry out the simulations of RBCs in complex flow problems. First, we develop the SDPD-IBM model in details, including the SDPD model for the evolving fluid flow, the RBC model for calculating RBC deformation force, the IBM for treating fluid-RBC interaction, and the solid boundary treatment model as well. We then conduct the verification and validation of the combined SDPD-IBM method. Finally, we demonstrate the capability of the SDPD-IBM method by simulating the flows of RBCs in rectangular, cylinder, curved, bifurcated, and constricted tubes, respectively.
在生物流体流动系统中，通常需要考虑复杂结构流体的流动问题，例如红细胞（RBC）通过复杂毛细血管的流动。基于粒子的平滑耗散粒子动力学（SDPD）是模拟此类复杂结构流体的一种简单灵活的方法。它结合了平滑粒子流体动力学（SPH）和耗散粒子动力学（DPD）的最佳特性，其参数具有特定的物理意义（来自 SPH 对纳维-斯托克斯方程的离散化），并结合介观模拟中的热涨落，类似于 DPD。另一方面，浸入边界法（IBM）是处理流固相互作用问题的首选方法，也被广泛用于处理 RBC 模拟中的血流 RBC 相互作用。在本文中，我们旨在将 SDPD 和 IBM 结合起来，以对复杂流动问题中的 RBC 进行模拟。首先，我们详细开发了 SDPD-IBM 模型，包括用于演化流体流动的 SDPD 模型、用于计算 RBC 变形力的 RBC 模型、用于处理流固相互作用的 IBM 以及固体边界处理模型等。然后，我们对组合的 SDPD-IBM 方法进行了验证和确认。最后，我们通过分别模拟 RBC 在矩形、圆柱、弯曲、分叉和狭窄管中的流动，展示了 SDPD-IBM 方法的能力。
