👉 The upper fluid, also referred to as the uppermost layer of a fluid system, is the part of the fluid that lies above the lower fluid and the interface between the two. It typically has a higher velocity and pressure compared to the lower fluid due to its exposure to external forces like gravity or flow through pipes. This layer can exhibit unique properties such as turbulence and shear stress, which are influenced by the fluid's viscosity, density, and the geometry of the system through which it flows. The upper fluid plays a crucial role in determining the overall behavior and dynamics of fluid systems, including heat transfer, mass transfer, and flow patterns.
