Types of Fluid Flow | A Brief Guide with Comparison

Types of fluid flow

On the basis of different flow conditions, fluid flow can be classified into various types.

1. Viscous and inviscid flow

One the basis of viscosity of fluid (in flow) we can classify fluid flows into two types.

• Viscous
• Inviscid (Non-Viscous)

In viscous flow, the resistance provided by viscosity is considerable.

In Inviscid flows, viscous resistance (to the flow of fluid) is negligible. In practice every fluid has some viscosity.

2. Internal and external flow

• When fluid is flowing inside a closed surface (like duct or pipe) it is called internal flow.
• When the fluid is flowing outside (on the surface of a body) it is called external flow.

3. Compressible and incompressible flow

• When the density of fluid varies it is known as compressible flow.
• When its density of fluid remains constant it is known as incompressible flow.

4. Laminar and turbulent flow

• When the flow of fluid is smooth and highly ordered then it is called laminar flow (Reynolds number less than 2300).
• When the flow of fluid is chaotic it is known as turbulent flow (Reynolds number greater than 4000).
• For Reynolds number greater than 2300 but less than 4000, a flow is known as Transitional flow.

5. Natural and forced flow

• When fluid is flowing due to the natural means like gravity, buoyancy etc. it is known as natural (or unforced) flow.
• When fluid is flowing with the help of some external power like that of pump or fan it is known as forced flow.

6. Steady and unsteady flow

• In steady flow, rate of flow (and other properties) of fluid remains constant with time.
• In unsteady flow, rate of flow (and other properties) of fluid varies with time.

7. Uniform and Non-uniform flow

• In uniform flow, rate of flow (and other properties) of fluid remains constant with location.
• In non-uniform flow, rate of flow (and other properties) of fluid varies with location.

8. One, two and three-dimensional flow

• In One-dimensional flow the fluid flows only in one-dimension (x, y or z dimension).
• In two-dimensional flow the fluid flows only in two-dimensions (xy, yz, xz etc.).
• In three-dimensional flow the fluid flows in all the three-dimensions.

Above are some important types of fluid flows which generally occur in nature.

Also read:

Working of wind turbine

Concept of windmill

What is a Turbine?

Featured image source: By Gary Settles – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=29522249