Fig. 5.6.2: Flow pattern for sharp-edged entrance.

The minor head loss is also produced when the fluid flows through these geometries enter into the reservoir (Fig. 5.6.1). These losses are known as exit losses. In these cases, the flow simply passes out of the pipe into the large downstream reservoir, loses its entire velocity head due to viscous dissipation and eventually comes to rest. So, the minor exit loss is equivalent to one velocity head , no matter how well the geometry is rounded.

Sudden Expansion and Contraction : The minor losses also appear when the flow through the pipe takes place from a larger diameter to the smaller one or vice versa. In the case of sudden expansion, the fluid leaving from the smaller pipe forms a jet initially in the larger diameter pipe, subsequently dispersed across the pipe and a fully-developed flow region is established (Fig. 5.6.3). In this process, a portion of the kinetic energy is dissipated as a result of viscous effects with a limiting case .

Fig. 5.6.3: Flow pattern during sudden expansion.