Direct numerical simulation of the flow in a flue pipe

etc15 Tracking Number 461

The flow behavior of a geometrically simplified flue pipe has been investigated by direct numerical simulation for jet Reynolds numbers of Re = 368; 490; 613. The flow process starts with the formation of a planar ring vortex at the flue exit, which travels towards the upper lip of the pipe. In the following Kelvin-Helmholtz instability appears at both sides of the jet, vortices are formed and an oscillating lateral movement of the jet set in. The vortices interacts with the upper lip, which leads to the generation of further opposite rotating vortices. After resonance is established in the pipe, the frequency spectrum of the quasi periodic state shows the expected fundamental frequency as well as several harmonics.