Collaborative Research: Understanding the Collective Effects in Suspensions of Vesicles, Capsules, and Particles

该项目代表了对囊泡、胶囊和胶囊/颗粒混合物的个体动力学和集体相互作用的全面研究。该合作研究是在高性能计算机（HPC）模拟多相流现象以及使用微流体和微流变学的详细实验之间的协同努力。仿真算法的新颖方面包括光滑粒子网格埃瓦尔德边界元素代码，该代码采用了变形和相互作用界面的频谱，环路细分和边界元素分辨率。基本上，界面建模中的任意剪切、弯曲和膨胀模量可以包括在内，从而允许在复杂的微流体几何形状中模拟从胶囊到囊泡（包括刚性颗粒和混合物）的全范围动力学。此外，非布朗悬架和布朗悬架可以用高分辨率的界面进行模拟。实验包括直接可视化，通过荧光显微镜，详细的囊泡随时间变化的动力学，并通过创造性的界面化学，具有不同剪切模量的胶囊在(a)微流控四辊轧机装置中（能够在一个滞止点附近重现任何平面混合流，在此点上囊泡/胶囊可能被困住并被观察更长时间）和(b)为检验集体悬浮动力学而设计的微通道几何形状。实验还将集中于测量，通过荧光显微镜和颗粒跟踪，剪切诱导的颗粒扩散和流变行为的约束长度尺度的变化。应用包括了解微循环中的血小板止血，以及用于医学应用的工程囊泡。

Award: 1066263PI: Shaqfeh/MullerThis project represents a comprehensive investigation of the individual dynamics and the collective interactions of vesicles, capsules, and capsule/particle mixtures. The collaborative research is a synergistic effort between high performance computer (HPC) simulations of multiphase flow phenomena as well as detailed experiments using microfluidics and microrheology. Novel aspects of the simulation algorithm include a smooth particle mesh Ewald boundary element code employing both spectral, Loop subdivision, and boundary element resolution of the deforming and interacting interfaces. Essentially, arbitrary shear, bending, and dilatational moduli in the interfacial modeling can be included thus allowing the full range of dynamics from capsules to vesicles including rigid particles and mixtures to be simulated in complex microfluidic geometries. Moreover, nonBrownian and Brownian suspensions can be simulated with high resolution of the interfaces. The experiments include direct visualization, via fluorescence microscopy, of the detailed time varying dynamics of vesicles, and, by creative interfacial chemistry, capsules with varying shear modulus in (a) the microfluidic four roll mill device (capable of reproducing any planar mixed flow in the vicinity of a stagnation point at which the vesicle/capsule may be trapped and observed for extended times) and (b) microchannel geometries designed for examination of collective suspension dynamics. Experiments will also focus on measurements, through fluorescence microscopy and particle tracking, of the shear-induced diffusion of particles and the rheological behavior as the confinement length scale is varied. Applications including understanding platelet hemostasis in the microcirculation as well as engineering vesicles for medical applications.