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

奖项：1066263 PI：Shaqfeh/Muller这个项目代表了对囊泡、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。这项合作研究是多相流现象的高性能计算机(HPC)模拟以及使用微流变学和微观流变学的详细实验之间的协同工作。该模拟算法的新方面包括光滑粒子网格Ewald边界元程序，该程序同时使用了变形和相互作用界面的谱、Loop细分和边界元分辨率。本质上，界面模拟中可以包括任意的剪切、弯曲和膨胀模数，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)的全范围的动力学。此外，可以用高分辨率的界面模拟非布朗和布朗悬浮液。这些实验包括通过荧光显微镜直接显示囊泡的详细时变动力学，以及通过创造性的界面化学，在(A)微流控四辊磨机装置(能够重现停滞点附近的任何平面混合流，囊泡/胶囊可以被捕获并长时间观察)和(B)为检查集体悬浮动力学而设计的微通道几何形状中，具有不同剪切模数的胶囊。实验还将集中于通过荧光显微镜和颗粒跟踪来测量剪切诱导的颗粒扩散和随着约束长度尺度的变化而产生的流变性。应用包括了解微循环中的血小板止血以及用于医疗应用的工程囊泡。

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.