# Difference between Kinematic and Dynamic Viscosity

Have you ever wondered what the difference is between kinematic and dynamic viscosity? Most people use these two terms interchangeably, but there is a big difference between the two. In this blog post, we will discuss what each term means and how to calculate them. By understanding the difference between kinematic and dynamic viscosity, you can more accurately determine the properties of fluids.

Contents

## What is Kinematic Viscosity?

Kinematic viscosity is a measure of a fluid’s resistance to flow and shear. It is commonly used to characterize a fluid’s viscous behavior, particularly when the fluid is non-Newtonian. The kinematic viscosity is equal to the dynamic viscosity divided by the fluid density. Kinematic viscosity is typically expressed in units of square meters per second (m^2/s). Kinematic viscosity is an important property of fluids that affects their Ability to flow and transport heat. A fluid with a high kinematic viscosity will have a high resistance to flow and will be reluctant to change shape in response to applied forces. Fluids with a low kinematic viscosity, on the other hand, will flow easily and will readily change shape. Kinematic viscosity also affects a fluid’s ability to transport heat. A fluid with a high kinematic viscosity will tend to have poor thermal conductivity, while a fluid with a low kinematic viscosity will have good thermal conductivity. Kinematic viscosity is therefore an important consideration in many engineering applications involving heat transfer.

## What is Dynamic Viscosity?

Dynamic viscosity is a fluid’s resistance to flow. It is measured in poises or, more commonly, centipoise (cP). The lower the number, the less viscous the fluid. For example, water has a dynamic viscosity of 1 cP, whereas honey has a dynamic viscosity of 2,400 cP. Dynamic viscosity is affected by both temperature and pressure. As temperature increases, dynamic viscosity decreases. This effect is most pronounced in low-viscosity fluids such as water. For example, water’s dynamic viscosity at 20°C is 1 cP, but at 50°C it is only 0.31 cP. Dynamic viscosity also increases with pressure; however, this effect is much less pronounced than the effect of temperature. Dynamic viscosity is an important property of fluids because it affects the fluid’s resistance to flow. The higher the fluid’s dynamic viscosity, the greater the fluid’s resistance to flow. This property is important in many applications, such as the design of pipelines and the determination of pumping requirements.

## Difference between Kinematic and Dynamic Viscosity

Kinematic viscosity is a measure of a fluid’s resistance to flow and shear stress. It is calculated as the ratio of dynamic viscosity to density. Dynamic viscosity, on the other hand, is a measure of a fluid’s resistance to deformation by shear or tensile stress. It is related to the fluid’s elasticity and is governed by Newton’s law of viscosity. The two measures are similar but have different applications. Kinematic viscosity is used when calculating velocity and Reynolds numbers, while dynamic viscosity is used in calculations involving stress and strain.

## Conclusion

In conclusion, kinematic viscosity is a measure of the resistance of a fluid to gradual deformation by shear stress, while dynamic viscosity is a measure of the fluid’s resistance to sudden changes in its shape. Kinematic viscosity is usually greater than dynamic viscosity, except when the fluids are near their boiling points.