Experimental investigation of turbulent natural convection flow in a converging channel

This paper reports the results of fluid flow measurements for natural convection in a converging plates channel using the particle image velocimetry (PIV) system. The channel walls were symmetrically subjected to uniform temperature conditions. Velocity characteristics were obtained for two inclination angles, θ = 15 and 45°, and two heating conditions corresponding to RaL = 2.7 × 108 and 4.4 × 108, where RaL is the Raleigh number based on the length of the channel wall. Results are presented as vector plots as well as profiles of mean velocities and turbulence quantities. They show that the main flow is aligned with the orientation of the channel walls, due to the effect of buoyancy force, which is no longer exclusively in the vertical direction. They also reveal the presence of reverse flow, which leads to the formation of two symmetric vortices in the core.