Flow reduction of synthetic screens obtained with both a water and airflow apparatus

Wind breaking cloths, ventilation screens and insect nettings reduce wind velocity and indoor ventilation because of their flow resistance which causes flow reduction. Knowledge of the flow reduction is important to compare materials and to predict their behaviour for specific applications. Flow reduction is defined as the difference in flow velocity with and without agrotextile, the other circumstances remaining the same. The flow reduction coefficient of an agrotextile is the flow reduction expressed as a percentage of the flow velocity without agrotextile. Some commercial agrotextiles were tested in both a water and airflow apparatus to determine their flow reduction coefficient. Since the flow of water and the flow of uncompressed air obey the same laws, similar results were obtained. Moreover, a relation was found between the open area of the fabrics and the flow reduction coefficient. (C) 1998 Silsoe Research Institute.