报告时间：2018 年 04 月 18 日(周三 ) 下午 16 :00

报告地点：物理大楼二层220 会议室

报告嘉宾：Pan JIA (贾攀 )  Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Orsay 91405, France

报告内容：Different patterns on a sublimating surface, such as penitentes and ice waves, have been observed on Earth. Some of them also form (or are expected to form) on other planetary bodies, such as on Mars and on Pluto. These patterns are always found in specific environments, where the partial pressure of vapor (corresponding to the ice substance) in the atmosphere is low, sublimation therefore significantly contributes to ablation and takes a part in the development of patterns on the ice surface. So far, the genesis of these patterns is still not completely known, and further work is needed to understand the role of sublimation in the development of such wavy patterns,the relevant dynamical mechanisms controlling the mass balance, the dynamics at different scales and so on. In this talk, a theoretical model will be presented for sublimation patterns based on the linear instability analysis by considering a flat solid surface which is slightly out of equilibrium with its vapor, submitted to a homogeneous and time independent wind. After

the model introduction,discussions will show four destabilizing mechanisms : diffusion/convection of heat, the blowing velocity from the surface, the Mullins-Sekerka instability associated with a thermal flux coming from the ice and the penitentes instability associated with self-illumination of the surface. In turn,from a Bernoulli-like effect, pressure turns out to be stabilizing.

嘉宾简介：Pan JIA is a LabEx PALM Research Fellow at Laboratoire de Physique des Solides (LPS, UMR 8502) in Université Paris-Sud in France. Before the present position, he did his PhD research under the supervision of Profs. B. Andreotti and P. Claudin in PMMH lab at ESPCI in Paris. His long-standing research interest has been on understanding the physics and mechanics of interfaces, involving hydrodynamics,elasticity/viscoelasticity, phase change and granular media.

报告信息网址 : https://www.physics.nwu.edu.cn

Contacts : 罗 昊 (luo@nwu.edu.cn)