At a constant flow rate, which liquid will have the highest droplet VMD?

The reasoning behind the choice of the liquid with the highest viscosity being associated with the highest droplet Volume Median Diameter (VMD) centers on the physical characteristics of liquids and how they behave under specific conditions during aerosolization.

Viscosity, which is a measure of a fluid's resistance to flow, plays a crucial role in the formation of droplets when a liquid is atomized for aerial application. A liquid with higher viscosity tends to form larger droplets. This occurs because the increased resistance to flow makes it more challenging for the liquid to break apart into smaller droplets during the atomization process. Consequently, at a constant flow rate, the liquid's higher viscosity contributes to a greater droplet size, leading to an increased VMD.

In contrast, liquids with lower viscosity more readily break apart during atomization, resulting in smaller droplets due to their lower resistance to flow. Therefore, as one considers the relationship between droplet size and viscosity, liquids with higher viscosity will yield a larger droplet VMD compared to those with lower viscosity. This principle is fundamental in aerial application practices, as it can influence the effectiveness and environmental impact of the pesticide being applied.