Efficient computation of micro-particle dynamics including wall effects
Efficient computation of micro-particle dynamics including wall effects
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DOI：
10.1016/j.compfluid.2003.06.002
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发表时间：
2004-05-01
影响因子：
2.8
通讯作者：
Buchanan, JR
中科院分区：
文献类型：
--
作者：
Longest, PW;Kleinstreuer, C;Buchanan, JR
本研究描述了一种有效的方法，单向耦合欧拉-拉格朗日模拟球形微尺寸颗粒，包括颗粒壁的相互作用和量化的近壁停滞在可能升高的浓度。重点是粒子血液动力学模拟，其中粒子悬浮液是由关键的血细胞，如单核细胞，和载体流体是非牛顿的。自适应时间步长积分的粒子运动方程，相关的点力模型条款，和适应表面诱导粒子力的任意三维几何形状的问题进行了概述。通过比较现有的实验轨迹，它表明，流体元件的路径线可以用来模拟稀释瞬态条件下从壁边界去除的非相互作用的血液颗粒。然而，当颗粒与壁面的相互作用很大时，就需要一个扩展形式的颗粒轨迹方程，其中包括斯托克斯阻力、近壁阻力修正或润滑力、压力梯度和近壁颗粒升力。尽管如此，额外的物理和/或生化壁力在纳米范围内不能很容易地计算，因此近壁停留时间（NWRT）模型表明血液颗粒沉积的概率。将该理论应用于股动脉旁路端侧吻合的虚拟模型，其中示出了基于拉格朗日的NWRT参数的轮廓，并验证了收敛性。为了有效地计算大量的粒子轨迹所需的解决区域的颗粒停滞，所提出的粒子跟踪算法存储在一个共享的内存架构（SGI起源2400）的所有瞬态速度场的解决方案数据，并计算粒子轨迹使用自适应并行方法。与市售的粒子跟踪软件包相比，所提出的算法能够将复杂循环流域中典型的瞬态单向耦合血液粒子模拟的计算时间减少一个数量级。(C)2003 Elsevier Ltd.保留所有权利。
This study describes an effective method for one-way coupled Eulerian-Lagrangian simulations of spherical micro-size particles, including particle-wall interactions and the quantification of near-wall stasis at possibly elevated concentrations. The focus is on particle-hemodynamics simulations where particle suspensions are composed of critical blood cells, such as monocytes, and the carrier fluid is non-Newtonian. Issues regarding adaptive time-step integration of the particle motion equation, relevant point-force model terms, and adaptation of surface-induced particle forces to arbitrary three-dimensional geometries are outlined. By comparison to available experimental trajectories, it is shown that fluid-element pathlines may be used to simulate non-interacting blood particles removed from wall boundaries under dilute transient conditions. However, when particle-wall interactions are significant, an extended form of the particle trajectory equation is required which includes terms for Stokes drag, near-wall drag modifications, or lubrication forces, pressure gradients, and near-wall particle lift. Still, additional physical and/or biochemical wall forces in the nano-meter range cannot be readily calculated; hence the near-wall residence time (NWRT) model indicating the probability of blood particle deposition is presented. The theory is applied to a virtual model of a femoral bypass end-to-side anastomosis, where profiles of the Lagrangian-based NWRT parameter are illustrated and convergence is verified. In order to effectively compute the large number of particle trajectories required to resolve regions of particle stasis, the proposed particle tracking algorithm stores all transient velocity field solution data on a shared memory architecture (SGI Origin 2400) and computes particle trajectories using an adaptive parallel approach. Compared to commercially available particle tracking packages, the algorithm presented is capable of reducing computational time by an order of magnitude for typical transient one-way coupled blood particle simulations in complex cyclical flow domains. (C) 2003 Elsevier Ltd. All rights reserved.