Development

We consider again a general stream tube:

Application – Fluid Striking a Flat Surface

Consider the jet of fluid striking the surface as shown:

Application – Flow around a bend in a pipe

Consider the flow around the bend shown below. We neglect changes in elevation and consider the control volume as the fluid between the two pipe joins.

This is the force and direction of the bend on the fluid. The bend itself must then be supported for this force. In practice a manhole is built at a bend, or else a thrust block is used to support the pipe bend.