THE EFFECT OF THE BOUNDARY LAYER SEPARATION IN Y-JUNCTION SHAPE

摘要

The work to be presented herein is a theoretical and numerical analysis of the complex fluid mechanism that occurs inside a Y-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. This paper shows a numerical analysis of boundary layer separation that occurs in an internal flow; the Y-junction shape. This research shows a numerical simulation of mapping the flow inside Y-junction shape flow. The results show that for small divergent angle namely less that 30-degree the flow separation is almost negligible and 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.