1. 제 목 : Formation of streamwise vortices by rotation of arch vortex





2. 연 사 : 나 양 교수 (건국대학교) 





3. 일 시 : 2001년 11월 13일(화) 16 : 00





4. 장 소 : 301동 1512호








5. 내 용 : Vortices, oriented in the streamwise direction, play an important role in generating Reynolds shear stress (and turbulence) for flow over a smooth wall. Many of these have been observed to originate from tiny streamwise vortices, located in the immediate vicinity of the wall. This paper identifies a different process that forms about 30 percent of the streamwise vortices at locations, away from the wall, in the middle of the viscous wall layer. This is accomplished by examining the changes, with time, of the turbulent field obtained from a direct numerical simulation of turbulent flow in a channel.


Streamwise vortices create a shear layer by pumping low momentum fluid from the wall. One or more small spanwise vortices are formed at the top of this layer. These grow in size and rotate in the direction of flow. A number of previous investigations have suggested that spanwise vortices could have a direct role in the formation of streamwise vortices.


This talk will describe a process by which this is accomplished.


 














6. 문 의 : 기계항공공학부 최 해 천 교수 (☏ 880-8361)