Simulating the dynamics of spray droplets in the atmosphere using ballistic and random-walk models combined

• Published in: Journal of wind engineering and industrial aerodynamics Vol. 67; pp. 923 - 933
• Main Authors: Mokeba, M.L., Salt, D.W., Lee, B.E., Ford, M.G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.04.1997; Elsevier Science
• Subjects: Applied sciences; Buildings. Public works; Climatology and bioclimatics for buildings; Computation methods. Tables. Charts; Computer simulation; Domestic appliances; Dynamics; Exact sciences and technology; Ground-based appliances; Mathematical models; Simulation; Spray drift; Spray droplets; Structural analysis. Stresses; Wind; Spray drift; Wind; Simulation; Dynamics; Ground-based appliances; Spray droplets; Computational fluid dynamics; Ground based measurement; Spraying; Aerodynamics; Velocity distribution; Evaporation; Ballistic transport; Droplet; Three dimensional model; Random walk model; Mixed model; Numerical simulation; Trajectory
• ISSN: 0167-6105; 1872-8197
• DOI: 10.1016/S0167-6105(97)00129-3

This paper presents a simulation model based on earlier work that combines both ballistic and random-walk models to describe the three-dimensional dynamics of spray droplets released in a specified direction from ground-based appliances in various weather conditions. The velocity of spray droplets is considered as a weighted sum of their ballistic and random-walk velocities scaled by a factor (1−β) and β, respectively, where β is defined as the ratio of the sedimentation velocity and the relative velocity between the spray droplets and the ambient wind speed. The contribution of the random-walk model to the initial velocity is seen to be negligible at first, but increases progressively, though not proportionally, as β increases. As soon as the spray droplets attain their sedimentation velocities, β = 1, the random-walk velocity component predominates and β plays no further part in the calculations. The predicted effects close to the sprayer of the drop size, wind velocity and direction, evaporation on the transport process have been evaluated and combined to provide an analysis of spray drift.