What causes minor head loss in fluid dynamics?

Minor head loss in fluid dynamics refers to the pressure loss that occurs when a fluid flows through components in a piping system that are not straight sections of pipe. This phenomenon is primarily caused by the presence of fittings, elbows, valves, and other changes in the system's geometry. As the fluid navigates these components, it experiences disturbances and turbulence, which results in energy loss, traditionally measured in terms of head loss.

When fluid travels through elbows and fittings, it encounters changes in direction and flow area, leading to an increase in friction and energy loss. These elements are often responsible for a significant portion of the overall head loss in a fluid transport system.

In contrast, high fluid velocity can lead to increased friction losses but is not classified as a source of minor head loss itself. While temperature changes can affect fluid viscosity and density, they do not specifically correlate to what is considered minor head loss in the context of fittings and flow disturbances. The expansion of the pipe diameter can reduce head loss by lowering the velocity and friction, again not contributing to minor head loss as described. Thus, the interaction of fluid with system components like elbows and fittings is what primarily drives minor head loss in fluid dynamics.