| Topic: | Receptivity of boundary-layer instability modes to external perturbations: comparison between supersonic and subsonic regimes |
|---|---|
| Speaker: | Dr Ming Dong Associate Professor, Department of Mechanics, Tianjin University, China |
| Date: | Monday, 20 January 2020 |
| Time: | 10.00am to 11.00am |
| Venue: | Seminar Room EA-06-02   (Block EA, Level 6) (map of NUS can be found at http://map.nus.edu.sg/) |
| Host: | Asst Prof Zhang Mengqi |
Abstract
Laminar-turbulent transition in boundary-layer flows is of fundamental importance due to its direct relevance to a variety of engineering applications such as aircraft designs. In the event of low-level environmental perturbations, boundary-layer transition follows a natural route, in which the normal modes undergo long-distance amplifications under linear regime. Receptivity, describing the excitation of the normal modes by external forcing, determines the initial condition of their late-time accumulation and thus is a crucial issue. In this talk, I will first review the previous work on the receptivity study in the recent forty years, and highlight the theoretical descriptions by the large-Reynolds-number asymptotic approach. Then, I will introduce the recent progress concerning with the receptivity of supersonic inviscid instability modes by the interaction of local roughness elements and freestream acoustic waves. Remarkable differences are observed in comparison with that in the subsonic regime, and the detailed interpretation will be provided as well.
About the Speaker
Dr. Ming Dong received his PhD degree from Tianjin University in 2008, and became a lecturer of Department of Mechanics, Tianjin University during 2008-2010. He was promoted to an associate professor in 2010. During 2013.9-2014.9, he spent one year in Department of Mathematics, Imperial College London as an academic visitor, and during 2016.2-2018.1, he was working there as a Marie Curie Fellow. His main research interests include hydrodynamic instability, hypersonic boundary-layer transition and aeroacoustics. He is used to applying asymptotic theory, combined with numerical techniques, to observe the intrinsic mechanism of the flow motion.