Author(s)

K. Alhussan

Abstract

Flow separation patterns in a 60-degree junction K. Alhussan Space Research Institute, King Abdulaziz City for Science and Technology, Saudi Arabia Abstract The work to be presented herein is a theoretical and numerical analysis of the complex fluid mechanism that occurs inside a 60o-junction shape specifically with regard to the boundary layer separation, vortex shedding and generation of wake. The boundary layer separates from the surface, forms a free shear layer and is highly unstable. This shear layer will eventually roll into a discrete vortex and detach from the surface. A periodic flow motion will develop in the wake as a result of boundary layer vortices being shed from the solid boundary. The periodic nature of the vortex shedding phenomenon can sometimes lead to unwanted structural vibrations, especially when the shedding frequency matches one of the resonant frequencies of the structure. A number of important conclusions follow from the current research. First, the study of the actual flow configuration inside 60o-junction shape offers some insight into the complex flow phenomena. Second, the characteristics of the boundary layer separation, the vortex and wake change considerably with the divergent angle. This research shows that downstream, away from the junction, the boundary layer reattaches and normal flow occurs, i.e. the effect of the boundary layer separation is only local. Nevertheless fluid downstream of the junction will have lost energy. The results show that downstream, away from the junction, the boundary layer reattaches and normal flow occurs, i.e. the effect of the boundary layer separation is only local. Nevertheless fluid downstream of the junction will have lost energy. This research shows that when the velocity ratio is equal to unity the circulation and the vortex shedding phenomenon are maximized. Keywords: flow separation, vortex flow, internal flow, boundary layer, numerical analysis, CFD.

Keywords

flow separation, vortex flow, internal flow, boundary layer, numerical analysis, CFD.