**What is Fluid Flow?**

Fluid Flow is a part of fluid mechanics and deals with fluid dynamics. Fluids such as gases and liquids in motion is called as fluid flow. Motion of a fluid subjected to unbalanced forces. This motion continues as long as unbalanced forces are applied.

For example, if you are pouring a water from a mug, the velocity of water is very high over the lip, moderately high approaching the lip, and very low at the bottom of the mug. The unbalanced force is gravity, and the flow continues as long as water is available and the mug is tilted.

**Types of Fluid Flow**

**Steady or Unsteady Flow: **Fluid flow can be steady or unsteady, depending on the fluid’s velocity:

**Steady:**In steady fluid flow, the velocity of the fluid is constant at any point.**Unsteady:**When the flow is unsteady, the fluid’s velocity can differ between any two points.

**Viscous or Nonviscous Flow: **Liquid flow can be viscous or nonviscous.

**Viscosity **is a measure of the thickness of a fluid, and very gloppy fluids such as motor oil or shampoo are called **viscous fluids**.

**Fluid Flow Rate**

ρ = density

V = Velocity

A = area

\(Flow \; rate = Area \times Velocity\)

**Fluid Flow Through a Pipe**

The general capacity of the pipes varies on its size. The table given below shows the capacity of the flow of fluid based on its size.

Pipe size (in inch) |
Maximum Flow (in gal/min) |
Velocity (in ft/s) |
Head Loss in (ft / 100 ft) |

2 | 45 | 4.3 | 3.9 |

2.5 | 75 | 5.0 | 4.1 |

3 | 130 | 5.6 | 3.9 |

4 | 260 | 6.6 | 4.0 |

6 | 800 | 8.9 | 4.0 |

8 | 1600 | 10.3 | 3.8 |

10 | 3000 | 12.2 | 4.0 |

12 | 4700 | 13.4 | 4.0 |

14 | 6000 | 14.2 | 4.0 |

16 | 8000 | 14.5 | 3.5 |

18 | 10000 | 14.3 | 3.0 |

20 | 12000 | 13.8 | 2.4 |

24 | 18000 | 14.4 | 2.1 |