Experimental and Numerical Investigation of Turbulent Natural Convection Flow in a Vertical Channel With a Heated Obstacle

Abstract

In the present study, experiments were carried out for natural turbulent convection induced by a heated square bar in a two-dimensional (2D) open vertical channel for dif ferent Rayleigh numbers and bar positions. For this purpose, particle image velocimetry (PIV) system has been employed to investigate the velocity field in the vertical center channel plane. The present work is also concerned with computational fluid dynamics (CFD) simulation by employing large Eddy simulation (LES) turbulence model, used in fire dynamic simulation (FDS) code. Calculations were performed for different chimney aspect ratios A* (height Lh over width d) and modified Rayleigh numbers ranging between 4 x 107 and 10s. Experimental and numerical results included mean velocity profiles; flow structure and Nusselt number were presented and discussed. To validate CFD code, velocity profiles along channel elevation were compared with our experimen tal measurements, and a good agreement was observed. Therefore, FDS code is a useful tool to simulate natural turbulent convection dynamic field, and consequently the thermal field in such situation. CFD code has been used to study the best heated bar location (corresponding to the best cooling effect) in the channel as well as the best airflow rate. This best location and its explanation are discussed in this paper.

LBM-MRT simulation of vertical flow of a non-Newtonian fluid in a channel provided with obstacles

“…In addition, we have shown that to prescribe w0 yields no significant difference between the wall heat fluxes calculated either for forced convection or for mixed convection When imposing an outlet pressure drop, natural convection assists effectively forced convection and the flow rate as well as the wall heat fluxes are systematically increased over those found for pure forced convection. Harnane et al [17] Under taken a numerical study of turbulent natural convection flow and heat transfer around a square bar with constant temperature has been performed in a vertical channel, using FDS code. The results show that the FDS code can qualitatively capture the structure of the flow field and quantitatively reproduces the mean velocities.…”