Analysis of nematic liquid crystal flows, high dimensional phase-transition, conserved geometric motion, and L-infinity variational problems

这个项目的目标是继续主要研究者对四个子领域的分析问题的研究：(I)向列相液晶材料的流体动力学流动，(Ii)两个流形之间的高维相变问题，(Iii)共维两个表面的守恒几何运动，和(Iv)L-无限变分问题。本项目的第一部分涉及模拟向列相液晶流体动力学流动的Ericksen-Leslie系统，该系统是一个介于基本流体速度场的不可压缩的Navier-Stokes方程和向列相液晶分子取向指向量场的调和映射的传输热流之间的强非线性耦合系统。目的是建立三维Leray-Hopf型弱解的存在性和部分正则性。第二个项目研究了奇异摄动泛函在Gamma收敛意义下的能量渐近性，并利用新边界条件下的调和映射热流和尖锐界面的平均曲率流来求解动力学上的Keller-Rubinstein-Sternberg问题。第三个项目是建立一般初始曲面的守恒平均曲率流的局部适定性。第四个项目是研究与空间相关的哈密顿函数的广义Aronsson方程的唯一性和无穷调和函数的正则性，以及与一致凸的哈密顿函数对应的Aronsson方程的正则性。所提出的问题不仅在数学上具有很大的挑战性，而且在生物、化学工程、物理、流体力学和材料科学等领域都有很强的联系和深刻的应用。从数学上讲，该项目所涉及的非线性偏微分方程或系统要么是高度退化的椭圆型问题，要么是具有超临界非线性的方程，它们的解肯定会提供在各种背景下有用的新思想和新技术。向列相液晶的流体动力学流动是描述粘弹性流体动力学的最基本方程之一，起源于LCD设计和工程。守恒的几何运动与玻色凝聚物理有着密切的联系。L-无穷大变分问题已在最优控制、图像恢复工程、确定化疗中的最优放射治疗以及随机博弈论的获胜策略设计等方面得到了应用。对这样一个系统的各种解的存在性和规律性的严格分析可以预测奇点的形成，使研究人员能够深入了解湍流现象，并证明应用科学家和工程师所做的计算和实验研究是合理的。该项目将出版面向研究人员和研究生的国际暑期学校的专著和讲稿，积极培训高级博士生，并组织具体会议，如俄亥俄河分析会议、AMS和SIAM特别会议以及AIM或BIRS讲习班。

The goal of this project is to continue the principal investigator's research on analytic issues arising from four subareas: (i) the hydrodynamic flow of nematic liquid crystal materials, (ii) high dimensional phase-transition problem between two manifolds, (iii) conserved geometric motion of co-dimension two surfaces, and (iv) L-infinity variational problems. The first part of this project deals with the Ericksen-Leslie system modeling hydrodynamic flow of nematic liquid crystals, which is a strongly nonlinear-coupled system between the incompressible Navier-Stokes equation of the underlying fluid velocity field and the transported heat flow of harmonic maps for the orientation director field of the nematic liquid crystal molecules. The objective is to establish existence and partial regularity for Leray-Hopf type weak solutions in dimension three. The second project investigates the energy asymptotic of a singularly perturbed functional in the sense of Gamma-convergence and resolve the Keller-Rubinstein-Sternberg problem on the dynamics in terms of harmonic map heat flow under new boundary conditions and mean curvature flow of the sharp interface. The third project is to establish the local well-posedness of such a conserved mean curvature flow for generic initial surfaces. The fourth project is to study the uniqueness of general Aronsson's equations for Hamiltonian functions with spatial dependence and the regularity of infinity harmonic functions and Aronsson's equations corresponding to uniformly convex Hamiltonians.The proposed problems in these areas are not only very challenging mathematically but also have strong connections and profound applications to other fields such as biology, chemical engineering, physics, fluid mechanics and material sciences. Mathematically, the nonlinear partial differential equations or systems involved in the project either are either highly degenerate elliptic problems or equations with super-critical nonlinearities whose resolutions will definitely contribute new ideas and techniques that will be useful in a variety of contexts. The hydrodynamic flow of nematic liquid crystals is among the most fundamental equations describing the dynamics of viscoelastic fluids and has its origination in LCD design and engineering. The conserved geometric motion has close connection with the Bose condensate physics. The L-infinity variational problems has found its applications in the optimal control, the image recovery engineering arise, the determination of optimal radiation treatments in chemotherapy, and the design of winning strategies for random game theories. Rigorous analysis of both the existence and the regularity of various solutions to such a system can predict the formation of singularities, allow researchers to gain insight into turbulent phenomena, and justify both computational and experimental studies made by applied scientists and engineers. This project will result in the publication of monographs and lecture notes from international summer schools for both researchers and graduate students, involve active training of advanced PhD students, and include the organization of specific conferences such as Ohio River Analysis Meetings, AMS and SIAM special sessions, and AIM or BIRS workshops.