Numerical investigation on the airflow characteristics and thermal comfort in buoyancy-driven natural ventilation rooms

Numerical simulations are conducted to model the transient development of the buoyancy-driven natural ventilation. The simulations are compared with experimental data and theoretical predictions in the literature to validate the numerical model. The airflow behavior of three cases, i.e., the initial indoor temperature is equal to, higher and lower than the outdoor temperature, were analyzed by the numerical results, respectively. The results show that transient flow development of the last case is relatively complex in naturally ventilated rooms with inner heat sources due to the transformation from downward ventilation to upward ventilation. Vent area, heat source power and vertical position of the source are the main factors affecting the airflow rate, vertical temperature difference in the occupied zone and indoor thermal comfort, while the vent shape and the horizontal position of heat source on the floor seem to have marginal influence on the transient natural ventilation. In addition, initial indoor temperature is also a crucial factor influencing the establishment of steady state of the transient ventilation besides the vent and heat source characteristics. (C) 2015 Elsevier B.V. All rights reserved.