Towards Computational Design of Chaotic, Unsteady Fluid Flows

题目：混沌非定常流动基于计算的工程设计
　　　Towards Computational Design of Chaotic, Unsteady Fluid Flows
报告人：王琪琪
　　　　Department of Aeronautics and Astronautics, MIT
时间：8月15日下午2:30
地点：力学一楼237房间（多媒体教室）

Unsteady flow simulations are playing an increasingly important role in aerospace engineering. Many types of flows, including turbulent mixing and 3D flow separation, can only be accurately simulated by capturing their unsteady, often chaotic dynamics. While simulation of these flows (using LES and hybrid RANS/LES) has been enabled by rapid growth of computer power, computational methods for design of unsteady flows is still at the frontier of research.

This talk presents my venture beyond just performing simulation of chaotic unsteady flows, towards aspects of computational design. These include optimization, control, uncertainty quantification, and data based inference. We will discuss challenges encountered in attempting this for chaotic unsteady flows. In particular, we will discuss sensitivity analysis -- a common method used in various aspect of computational design. 
Sensitivity analysis computes derivatives of simulation outputs to input design or uncertain parameters; existing methods for sensitivity analysis fundamentally fails in chaotic unsteady flows. This is primarily due to exponential growth of small perturbations, known as the "butterfly effect" of chaos. New computational algorithms for solving these challenges will be presented with preliminary results.
 
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