Specific Force
As per the momentum equation, the algebraic sum of all external forces acting in a given direction on a fluid mass is equal to the time rate of change of linear momentum of the fluid mass in that direction.
Also, dividing the equation by y, we get,
Note:
Critical flow is characterized by the following condition:
- Specific energy is minimum for a given discharge.
- Specific force is minimum for a given discharge.
- Velocity head is equal to half the hydraulic depth.
- Froude number is equal to unity.
- The discharge is maximum for a given specific energy.
