Numerical simulation of the airflow and temperature distribution in a tunnel greenhouse equipped with insect-proof screen in the openings

An analysis of the ventilation process in a tunnel greenhouse equipped with an insect-proof screen in the side openings was performed with the use of a commercial computational fluid dynamics (CFD) package (CFD2000(R)). The aim of the study was to investigate how the screen influences airflow and temperature patterns inside the greenhouse. The screens on the greenhouse inlets and outlets, as well as the crop were simulated using the porous medium approach. The first simulations were carried out with a wind direction perpendicular to the side openings. Insect screens significantly reduced airflow and increased thermal gradients inside the greenhouse. Maximum air velocity values inside the greenhouse were observed near the openings, whereas air velocity was lowest in the middle of greenhouse. Airflow rates reduced by half in the greenhouse equipped with screen, These differences were also important in the region covered by crop, thus screen affected the sensible and latent exchanges between crop and air. The effect of different wind directions was also investigated. Wind direction considerably affected climatic conditions inside the greenhouse, as contrasted air flow and temperature patterns were observed for various wind regimes, especially when the greenhouse was equipped with insect screens. (C) 2002 Elsevier Science B.V. All rights reserved