Nonlinear Stability of Gaseous Stars

主讲人:罗涛
时间: 周五16:30-17:30,2019-4-19
地点:清华大学近春园西楼三层报告厅

摘要

In the Newtonian mechanics frame work, the motion of a gaseous star is modelled by the PDEs of compressible Euler-Poisson or Navier-Stokes-Poisson equations. The nonlinear stability of two equilibrium configurations, rotating and non-rotating star solutions, will be discussed in this talk.
The rotating star solutions are those for the Euler-Poisson equations with prescribed total mass and angular momentum (or angular velocity), for which the nonlinear orbital stability will be discussed from the energy-minimizing point of view, by using the approach developed by Arnold for Hamiltonian systems, using the conservative laws of total mass, energy and angular momentum.
The key issue here is that the energy functional is not positive definite. This part consists of the nonlinear orbital stability for both the polytropic stars and white dwarfs with the total mass beneath the Chandrasekhar limit, based on the joint work with J. Smoller.
The second part of this talk is on the nonlinear asymptotic stability of non-rotating viscous gaseous stars in the framework of the free boundary problem of compressible Navier-Stokes-Poisson equations with physical vacuum singularity, based on the joint work with Zhouping Xin and Huihui Zeng.
The key issue here is to deal with the strong degeneracy of the system near vacuum states and identify the suitable higher order nonlinear weighted functional to establish the higher order regularity uniform both in time and all the way up to the vacuum boundary.

报告人简介

罗涛教授于1995年获得中国科学院博士学位。在加入香港城市大学前,他曾执教于美国乔治城大学。
 
罗涛教授的研究方向和学术兴趣主要为非线性偏微分方程,流体力学的数学理论,双曲守恒律,激波理论,变分原理,广义相对论。他曾获得多个学术奖项,包括中国科学院院长奖学金特别奖、美国密歇根大学Rackhan研究基金、意大利CNR研究基金、法国CNRS研究基金。
Professor Luo received his Ph.D. from Chinese Academy of   Sciences in 1995. He held a professorship at Georgetown University before   joining the City University of Hong Kong. His research interest is mainly in   the analysis of nonlinear partial differential equations in fluid mechanics.
 
He has received many   academic rewards including the Dean’s Special Award from Chinese Academy of Sciences, the Rackham   Fund of the University of Michigan, the Italian CNR (National Research Council) Fund, and French CNRS Research Fund.
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