SIMULATION OF DRIFT OF DISCRETE SIZES OF WATER DROPLETS FROM FIELD SPRAYERS

The drift distances of water droplets from field sprayers were determi ned for several variables with a computational fluid dynamics computer program. The simulation variables for drift distances up to 200 m inc luded: droplet size (10 to 2000 mu m), wind velocity (0.5 to 10.0 mls) , initial droplet velocity (0 to 50 mis), discharge height (0.25 to 4. 0 m), temperature (100 to 30 degrees C), relative humidity (10 to 100% ), and 20% turbulence intensity. Except at low temperature and high re lative humidity, all 50-mu m-diameter and smaller droplets completely evaporated before depositing 0.5 m below the point of discharge for al l simulated conditions. Drift distances increased with increasing wind velocity and discharge height, but decreased with increasing initial downward droplet velocity for 100-mu m-diameter and larger water dropl ets. Changes in ambient temperature and relative humidity had much gre ater influence on drift distances of water droplets less than 100-mu m -diameter than on 200-mu m-diameter and larger droplets.