Kinetic vs. Dynamic Viscosity

Kinetic viscosity and dynamic viscosity are two related but distinct concepts in fluid mechanics:

1. Dynamic Viscosity (Absolute Viscosity):
   - Dynamic viscosity, often simply referred to as viscosity, is a measure of a fluid's resistance to shear or flow when subjected to an applied force.
   - It represents the ratio of the shearing stress to the velocity gradient in a fluid flow.
   - It is denoted by the symbol μ (mu) and has units of Pa·s (Pascal-seconds) or N·s/m² (Newton-seconds per square meter) in the SI system.
   - Dynamic viscosity is the most commonly used measure of viscosity and is usually what people mean when they refer to "viscosity" without specifying.

2. Kinematic Viscosity:
   - Kinematic viscosity is a measure of a fluid's resistance to flow under the influence of gravity.
   - It is the ratio of dynamic viscosity (μ) to fluid density (ρ), and it represents the fluid's ability to flow due to its own weight.
   - It is denoted by the symbol ν (nu) and has units of m²/s (square meters per second) in the SI system.
   - Kinematic viscosity is particularly useful in applications where gravitational effects dominate, such as in the study of fluid flow in pipes or channels.

In summary, dynamic viscosity measures a fluid's resistance to shear stress, while kinematic viscosity takes into account the fluid's density and measures its resistance to flow under the influence of gravity.

~Written by ChatGPT.