Interferometric Study of Transient Natural Convection in Open Enclosure with Square Obstacle

An experimental and numerical investigation on transient natural convection in a partially open square enclosure with a rectangular adiabatic obstacle is reported in the present study. The enclosure contains a heat source positioned on center of bottom horizontal wall, a partial opening on left vertical wall, and a rectangular obstacle located on center of the enclosure. The experimental analysis is conducted using a Mach-Zehnder interferometer, whereas numerical simulation is performed using ANSYS Fluent 2020. Evolution of thermal plumes, flow phenomena, and average Nusselt number with time and Rayleigh number is reported. Also, a comparative analysis of steady-state heat transfer and flow phenomena without/with obstacle is illustrated. Temperature field in the investigating domain is observed by interpretation of interferograms obtained from experiments. Fringe patterns spread from heat source to across the cavity as time progresses, and its evolution with time is fast and irregular at higher Rayleigh numbers. Average Nusselt number is higher for enclosure with an obstacle, and the average increment is up to 13% compared to without any obstacle. Increment in average Nusselt number increases as Rayleigh number increases. In the case of obstacle, maximum velocity increases up to 19%, whereas maximum temperature decreases by about 5%.