A Numerical Study of the Effect of Natural Ventilation Displacement on the Buoyant Thermal Plume Evolution in an Enclosure

This numerical study deals with the evolution of a buoyant axisymmetric thermal plume issued from localized source in enclosure. The geometry configuration and the physical conditions in the confined space are the same as those chosen by Abdalla et al. (Eng. Appl. Comput. Fluid Mech. 3(4):608–630, [1]). It is aimed to analyze the influence of the natural displacement on development of thermal buoyant plume in a room connected to the exterior via high and low openings. It is sought to find the critical height at which stratification disappears when varying the airflow rate value. The buoyancy driven natural ventilation in an enclosure is modeled using the ICEM-CFD software11. The numerical results are obtained for two turbulence models based on Reynolds-Averaged Navier-Stokes (RANS): standard k-ε model and SST model. The results consistency is checked by comparisons to experimental and theoretical data. It is found that before equilibrium, ventilation velocity causes a transitional and turbulent mixing. The steady state is reached when air stratification is fully established leading to interface appearance separating the dense fresh air from the light warm buoyant air in lower and upper layers respectively. Furthermore, it is noted that the interface height is independent from the thermal source strength but depends strongly on the supplying fresh air velocity.