Two-dimensional numerical simulation of natural ventilation tn a multi-span greenhouse

The natural ventilation system far a four and one-half span commercial gree nhouse was evaluated using a computational fluid dynamics (CFD) model, Flue nt 4.3. Wind direction, wind speed, vent opening sizes, and the presence of plants on benches were all evaluated for their influences on natural venti lation rates and airflow distributions. Considering a target ventilation ra te of 0.75 to 1.0 volume per minute (A.C. min(-1)) for a comparable ventila tion system, the greenhouse was predicted to achieve an optimum natural ven tilation rate of 0.75 A.C. min(-1) when the wind speeds from the west were 2.4 m s(-1) and 2.1 m s(-1) with and without the plants, respectively! This same ventilation rate was predicted to be obtainable when the wind speeds from the east were 3.6 m s(-1) and 3.5 m s(-1) with and without the plants, respectively: Considering the full spans called the first, second, third, and fourth span from west to east, the side vent and the fourth I oof vent were predicted to act as primary inlet and largest outlet of airflows, resp ectively for the west wind. For an east wind, the fourth roof vent was pred icted to be the primary inlet and the side vent and first roof vent, were p redicted to be the primary outlets.