Newtonian Fluid vs. Non-Newtonian Fluid

Attribute	Newtonian Fluid	Non-Newtonian Fluid
Viscosity	Constant viscosity	Viscosity can change with shear rate
Flow behavior	Follows Newton's law of viscosity	Does not follow Newton's law of viscosity
Response to stress	Linear response to stress	Non-linear response to stress
Examples	Water, air	Ketchup, toothpaste

Definition

Newtonian fluids are defined as fluids that have a constant viscosity, regardless of the shear rate or stress applied to them. This means that their viscosity remains the same whether they are being poured slowly or quickly. On the other hand, non-Newtonian fluids do not have a constant viscosity and their flow behavior can change depending on the stress or shear rate applied to them. This means that their viscosity can vary as they are being poured or stirred.

Viscosity

One of the key differences between Newtonian and non-Newtonian fluids is their viscosity. Newtonian fluids have a constant viscosity, which means that their resistance to flow remains the same regardless of the force applied to them. This makes them easier to predict and work with in various applications. Non-Newtonian fluids, on the other hand, have a variable viscosity that can change depending on the force applied. This makes their behavior more complex and harder to predict.

Shear Rate

Another important attribute to consider when comparing Newtonian and non-Newtonian fluids is their response to shear rate. Newtonian fluids have a linear relationship between shear stress and shear rate, meaning that their viscosity remains constant regardless of the shear rate applied. Non-Newtonian fluids, however, do not follow this linear relationship and their viscosity can change with the shear rate. This means that non-Newtonian fluids can exhibit shear-thinning or shear-thickening behavior, depending on the conditions.

Examples

Examples of Newtonian fluids include water, air, and most oils. These fluids have a constant viscosity and their flow behavior is predictable under different conditions. Non-Newtonian fluids, on the other hand, include substances like ketchup, toothpaste, and blood. These fluids can exhibit different flow behaviors depending on the stress or shear rate applied to them, making them more complex to work with in various applications.

Applications

Newtonian fluids are commonly used in applications where a constant viscosity is desired, such as in hydraulic systems, lubrication, and fluid dynamics research. Their predictable flow behavior makes them ideal for these types of applications. Non-Newtonian fluids, on the other hand, are used in a wide range of applications where their variable viscosity is beneficial. For example, they are used in food processing, cosmetics, and pharmaceuticals, where their flow behavior can be tailored to specific needs.

Conclusion

In conclusion, Newtonian and non-Newtonian fluids have distinct attributes that make them suitable for different applications. Newtonian fluids have a constant viscosity and predictable flow behavior, while non-Newtonian fluids have a variable viscosity that can change with the shear rate. Understanding the differences between these two types of fluids is important for choosing the right fluid for a specific application and ensuring optimal performance.