nonentrained

Nonentrained describes particles, droplets, or parcels of fluid that do not become incorporated into a moving flow through the process of entrainment. Entrainment is the transfer of ambient fluid into a jet, plume, spray, or other flow, which leads to mixing, dilution, and changes in momentum. By contrast, nonentrained elements stay outside the mixing region and may maintain their initial velocity, temperature, or composition unless other forces act on them.

In fluid dynamics, entrainment governs how jets and plumes grow and dilute as they propagate. Components that are nonentrained may continue on a relatively undisturbed path, or gradually separate due to gravity, buoyancy, or shear. The concept helps describe situations where not all surrounding material is drawn into the moving flow, affecting predictions of concentration, temperature, or pollutant spread.

In atmospheric science, nonentrained air masses can influence cloud formation and plume behavior by limiting the mixing of dry or stable air with rising convection. In industrial processes, nonentrained solids or droplets in sprays, combustors, or mixers can impact efficiency, heat transfer, and emissions if they fail to be carried along by the intended flow.

Terminology varies by field, but the core idea remains: nonentrained elements are those that do not participate in the main entrainment-driven mixing of a flow. Quantitative assessment often involves comparing the rate of entrainment to other forces acting on the component, such as gravity, inertia, or buoyancy.