受002全讯白菜网国际合作处及数学系杨畅博士的邀请，法国图卢兹第三大学Fabrice Deluzet高级研究工程师于7月18日至28日访问公司并讲学，欢迎老师和同学与其讨论交流。

报告题目1：Multiscale models and Asymptotic Preserving methods for plasma physics, Asymptotic Modeling and  quasi-neutral limit

报告时间：2016年7月25日 上午9:00

报告地点：数学系会议室（格物楼503）

报告摘要：In this talk, we give an overview of numerical methods efficient for singular limits arising in plasma physics. The equations describing the coupled evolution of the plasma and the electromagnetic field contains space and time scales with different magnitude at the origin of difficulties for the derivation of efficient numerical methods, the discretization parameters being somehow constraints by these small scales. In numerous applications the scales of interest are large compared to the smallest ones described by the system.

The ratio of these two typical scales defines an asymptotic parameter spanning eventually a large range of values. To construct efficient numerical methods, a first approach consists in deriving, thanks to the asymptotic analysis, a reduced model, in which the smallest scales are filtered out from the equations. Such asymptotic models easily gives rise to numerical methods with discretization parameters that can be chosen arbitrarily with respect to the smallest scales of the original problem. The weakness of this approach lies in the limited validity of this reduced reduced equations. Indeed, the asymptotic model cannot provide an accurate approximation of the solution for asymptotic parameters of order one. Another path rely on implicit discretization of the multi-scale problem in order to cancel some of the more restrictive constraints on the discretization parameters. However, this approach is inefficient in the context of singular limits, for which the system is degenerate and does not allow for the computation of all the unknowns for vanishing asymptotic parameters.

We therefore present a class of numerical method, referred to as Asymptotic-Preserving methods, developed to address these singular limits.

报告题目2：Asymptotic modeling and efficient numerical method for magnetized plasmas : Drift asymptotic and anisotropic elliptic or diffusion equations

报告时间：2016年7月25日 上午10:00

报告地点：数学系会议室（格物楼503）

报告摘要：In this second talk, the concepts of Asymptotic Preserving schemes will be developed to different singular limits. The first one is specific to tokamak characterized by hot plasmas under intense magnetic fields. The second singular limit is also related to magnetized plasmas and anisotrop elliptic or diffusion equations arising in magnetized plasmas. Two context will be presented, the simulation of ionospheric and tokamak plasmas.

报告人简介：

F. Deluzet在求解流体方程和动力学方程邻域有多年的丰富经验。在计算数学著名期刊中,发表过多篇关于等离子体数学建模、渐近(AP)算法的高水平文章。