Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Chem Phys. 2011 Jan 21;134(3):034905. doi: 10.1063/1.3521395.
We develop and validate an efficient lattice kinetic Monte Carlo (LKMC) method for simulating particle aggregation in laminar flows with spatially varying shear rate, such as parabolic flow or flows with standing vortices. A contact time model was developed to describe the particle-particle collision efficiency as a function of the local shear rate, G, and approach angle, θ. This model effectively accounts for the hydrodynamic interactions between approaching particles, which is not explicitly considered in the LKMC framework. For imperfect collisions, the derived collision efficiency [ɛ=1 - ∫(0)(π/2) sinθ exp(-2cotθΓ(agg)/G)dθ] was found to depend only on Γ(agg)∕G, where Γ(agg) is the specified aggregation rate. For aggregating platelets in tube flow, Γ(agg)=0.683 s(-1) predicts the experimentally measured ε across a physiological range (G = 40-1000 s(-1)) and is consistent with α(2b)β(3)-fibrinogen bond dynamics. Aggregation in parabolic flow resulted in the largest aggregates forming near the wall where shear rate and residence time were maximal, however intermediate regions between the wall and the center exhibited the highest aggregation rate due to depletion of reactants nearest the wall. Then, motivated by stenotic or valvular flows, we employed the LKMC simulation developed here for baffled geometries that exhibit regions of squeezing flow and standing recirculation zones. In these calculations, the largest aggregates were formed within the vortices (maximal residence time), while squeezing flow regions corresponded to zones of highest aggregation rate.
我们开发并验证了一种高效的格子动力学蒙特卡罗（LKMC）方法，用于模拟具有空间变化剪切率的层流中的颗粒聚集，例如抛物线流或具有驻点涡的流动。开发了接触时间模型来描述颗粒-颗粒碰撞效率作为局部剪切率 G 和接近角θ的函数。该模型有效地考虑了接近颗粒之间的流体动力学相互作用，而这在 LKMC 框架中并未明确考虑。对于不完全碰撞，推导出的碰撞效率[ɛ=1-∫(0)(π/2)sinθexp(-2cotθΓ(agg)/G)dθ]仅取决于Γ(agg)∕G，其中Γ(agg)是指定的聚集速率。对于在管流中聚集的血小板，Γ(agg)=0.683 s(-1)预测了在生理范围内（G=40-1000 s(-1))测量到的ε，并且与α(2b)β(3)-纤维蛋白原键动力学一致。在抛物线流中，聚集导致最大的聚集体在壁附近形成，那里的剪切率和停留时间最大，然而，壁和中心之间的中间区域由于靠近壁的反应物耗尽而表现出最高的聚集率。然后，受狭窄或瓣状流动的启发，我们使用此处开发的 LKMC 模拟来研究具有挤压流和驻留再循环区的挡板几何形状。在这些计算中，最大的聚集体在涡旋内形成（停留时间最大），而挤压流区域对应于最高聚集率的区域。
