Guo Xin Born in 1981, he received B.S. degree from Nanjing University of Aeronautics and Astronautics in 2004. Now he is a Ph.D. candidate in the same university. His main research interest lies in computational fluid dynamics and flow stability. E-mail: guoxincn@sina.com Corresponding author. Tel: +86-25-84892624. E-mail address: tangdbin@ 163.com