What is the Difference Between Newtonian and Non Newtonian Fluids?

The main difference between Newtonian and non-Newtonian fluids lies in their response to applied force and their viscosity behavior. Here are the key differences:

• Newtonian Fluids:
• Obey Newton's law of constant viscosity, meaning their viscosity remains constant regardless of the amount of shear applied for a constant temperature.
• Examples include water, mineral oil, gasoline, and alcohol.
• Display a linear relationship between viscosity and shear stress.
• Non-Newtonian Fluids:
• Do not follow Newton's law of viscosity.
• When shear is applied, the viscosity of non-Newtonian fluids decreases or increases, depending on the fluid.
• Examples include ketchup, toothpaste, butter, cheese, cosmetics, and soap solutions.
• Can be further categorized into groups based on their viscosity behavior, such as shear-thinning (viscosity decreases with increased shear stress) or shear-thickening (viscosity increases with increased shear stress) fluids.

It is essential to understand the properties of the fluids you are working with, as their behavior plays a significant role in sizing and selecting equipment and proper fluid handling.

Comparative Table: Newtonian vs Non Newtonian Fluids

The main difference between Newtonian and non-Newtonian fluids lies in their viscosity behavior under shear stress. Here is a table comparing their key characteristics:

Newtonian fluids, such as water and mineral oil, have a constant viscosity and follow Newton's law of viscosity, meaning their viscosity remains constant regardless of the applied shear stress. On the other hand, non-Newtonian fluids, like ketchup and molten polymers, do not follow Newton's law of viscosity, and their viscosity changes with the applied shear stress.