Continuity equation describes the phenomenon of fluid flow through a pipe converse mass.

Let us consider the conservation of mass in closed system. So, we get the following equation-

A_{1}V_{1}_{1}t = A_{2}V_{2}_{2}t

Or,

A_{1}V_{1}_{1} = A_{2}V_{2}_{2}

Where,

A_{1} ,A_{2} = Cross-sectional area at inlet and outlet of the given pipe

V_{1} ,V_{2} = Velocities at inlet and outlet of pipe

_{1} ,_{2} = Densities of liquid at inlet and outlet of pipe

Consider Fig. 4.4 shows flow of an incompressible fluid,

In case of incompressible fluid, we know that densities are same at inlet and outlet-

Hence,

_{1} =_{2}

From the above equation,

**A _{1}V_{1}**

**Links of Previous Main Topic:-**

- Vapour compression refrigeration cycle introduction
- Basic fluid mechanics and properties of fluids introduction
- Fluid statics introduction
- Manometers measurement pressure
- Fluid kinematics
- Lagrangian method for describing fluid method
- Eulerian method for describing fluid method
- Lagrangian relationship from eulerian equations
- Steady and unsteady flows
- Uniform and non uniform flows
- Stream line
- Path lines

**Links of Next Mechanical Engineering Topics:-**