Which property of a spray mixture refers to the ability to maintain shape under flow conditions?

The ability of a spray mixture to maintain its shape under flow conditions is most accurately described by extensional viscosity. This property relates to how a fluid behaves when it is subjected to stretching or elongation forces, which is particularly relevant in spray applications where the mixture is dispersed into a fine mist. In aerial application, maintaining the shape of droplets as they are ejected from the nozzle is crucial for achieving uniform spread and effective coverage on the target area.

Extensional viscosity is vital for optimizing spray patterns and droplet formation, especially in situations where the fluid experiences high flow rates and acceleration. Understanding this property helps aerial applicators in selecting the right formulations that will perform optimally in the field.

While viscosity also relates to a fluid's resistance to flow, and surface tension describes the intermolecular forces at the surface of a liquid, neither captures the specific behavior of a fluid in the context of droplet formation and stability under dynamic flow conditions as effectively as extensional viscosity does. Dynamic surface tension concerns how surface tension changes with flow, but it isn’t specifically about maintaining shape under flow like extensional viscosity.