Which phenomenon is characterized by a decrease in flow rate due to friction?

Viscous drag is the phenomenon characterized by a decrease in flow rate due to friction, specifically the resistance that occurs when a fluid flows over a surface. This type of drag arises from the cohesive forces between the fluid molecules and the surface of the object, resulting in energy loss as the fluid moves. When a fluid flows over a surface, the inner layers move faster than the outer layers, which experience more resistance due to the frictional forces at play.

This friction causes a reduction in the effective flow rate, impacting the performance and efficiency of vehicles, particularly in aviation and marine applications where drag significantly affects speed and fuel consumption. The impact of viscous drag becomes particularly important at lower speeds and in laminar flow conditions, where the fluid does not mix rapidly.

In contrast, inertial drag is related to the mass of the fluid and its acceleration, wave drag is associated with the formation of waves in fluid dynamics, and induced drag arises from the generation of lift and is affected by factors like aspect ratio and angle of attack. These phenomena do not specifically relate to the straightforward frictional reduction in flow rate that viscous drag entails.