题目：Compressible Rayleigh-Taylor Instability in Cylindrical Geometry
报告人 ： 俞慧丹  博士
CCS-2: Computational Physics Group, Computer and Computational Science Division
Los Alamos National Laboratory, New Mexico, USA

报告内容摘要：
We study Rayleigh-Taylor instability (RTI) between two immiscible compressible fluids in cylindrical geometry at early times, using a linear stability analysis. 3D cylindrical as well as 2D axisymmetric and 2D circular unperturbed interfaces are considered and compared to the Cartesian case with planar interface. Focuses are on the effects of compressibility and geometrical convergence (or divergence) on the instability growth and the differences between implosion (acceleration acting inward) and explosion (acceleration acting outward). Compressibility can be characterized by two parameters -- static Mach number based on isothermal sound speed and ratio of specific heats - which in general have opposite influence, stabilization and destabilization, on the instability growth, similar to the Cartesian case. In general, instability is found to grow faster in the 3D cylindrical case than in the Cartesian case in implosion but slower in explosion; the difference between implosion and explosion is profound for the cylindrical cases but marginal for planar interface. The 2D axisymmetric case is consistently similar to the 3D cylindrical case, whereas as the flow transitions from 3D to the 2D circular case the results can be similar or opposite depending on the Atwood number, interface radius, and compressibility parameters. Thus, 2D circular calculations do not represent a useful model for the fully 3D cylidrical case. The instability development in the nonlinear and fully turbulent stages might be solved by lattice Boltzmann method with newly formulated lattice Boltzmann equation.

主持人：唐少强  教授
时间：12月23日（周二）下午2:00
地点：资源西楼2522报告厅（南门外东行50米，风入松楼上5层）

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联系人：刘才山  62756177

报告人简介：
Huidan Yu’s undergraduate major was in Physics, and she was a faculty member in China for over 10 years, culminating in a promotion to Professor immediately before she moved into the US in 2001. She has successively completed two Ph. D. programs; one in Physics from Peking University in 2001, China (Supervisor: Prof. Kaihua Zhao); and, another in Aerospace Engineering from Texas A&M University in 2004, USA (Supervisor: Prof. Sharath S. Girimaji). She is now working at Los Alamos National Laboratory (LANL) as a Research Associate.
Huidan Yu's research expertise is in multi-scale/multi-physics modeling and computation for fluid and thermal science on both mesoscopic and macroscopic levels. Prior to the LANL employment, She was dedicated herself to the development of lattice Boltzmann method, a novel computation tool based on kinetic theory, for complex flows. Her current project at LANL is to study theoretically, and numerically, turbulence and mixing in convergent geometries driven by interfacial instability, which impacts on nuclear energy technology.  Her research over the years has produced twenty-two prestigious journal papers, ten invited lectures, and fourteen conference papers.