COMPUTER ASSISTED VENTILATION OPTIMIZATION IN NARROW AND LONG SINGLE-SPAN GREENHOUSES IN YANGTZE RIVER DELTA VIA CFD SIMULATION

In the Yangtze River Delta, weak summer wind conditions often lead to inadequate air circulation in greenhouses, particularly in narrow and elongated single-span structures, negatively affecting crop growth. This study combines computational fluid dynamics (CFD) simulations with experimental validation to optimize the ventilation performance of such greenhouses. The validated CFD model (RMSE = 1.55, MAE = 1.09) analyzed three cases: baseline (no side windows), and two designs with 45° and 90° side window openings. The original greenhouse design without side windows was called Case A. In Case A, the average indoor wind speed in the modeling condition was 0.38m/s; there were 9 points with less than 0.3m/s. Redesign simulation experiments were carried out by adding side windows to the greenhouse; the openings were set to 45° and 90°, respectively. The case with 45° side windows was called Case B, and the case with 90° side windows was called Case C. Results show significant improvements in airflow, with average wind speeds increasing from 0.38 m/s (baseline) to 1.71 m/s (90° window). Ventilation efficiency also varied with external wind speed and direction. When the vector of the direction in the east-west direction increases, the average wind speed in the greenhouse increases. In Case A, the east-west direction vector component increased from 34% to 99%, resulting in a slight rise of 0.15 m/s in greenhouse wind speed. In Case B, the same vector increase led to a substantial 1.21 m/s rise in indoor wind speed. Case C also saw the vector increase from 34% to 99%, contributing to a 1.03 m/s increase in average indoor wind speed. These findings offer practical design guidance to enhance natural ventilation in narrow single-span greenhouses in low-wind regions.