Dynamic Viscosity
Introduction
Dynamic viscosity, denoted by the Greek letter μ, is a measure of a fluid's resistance to shear or tangential stress. It is a fundamental property of fluids, which includes both liquids and gases, and is a crucial parameter in many fluid-related engineering and scientific applications.
Definition
Dynamic viscosity is defined as the ratio of shear stress to shear rate. It is a measure of the internal friction resulting when one layer of fluid is made to move in relation to another layer. The SI unit of dynamic viscosity is the pascal-second (Pa·s), but the more common unit is the centipoise (cP).
Measurement
Dynamic viscosity can be measured using several methods, including capillary viscometers, rotational viscometers, and oscillatory rheometers. Each method has its advantages and disadvantages, and the choice of method depends on the specific requirements of the application.
Factors Influencing Dynamic Viscosity
Dynamic viscosity is influenced by several factors, including temperature, pressure, and the specific characteristics of the fluid. For most fluids, viscosity decreases with increasing temperature and increases with increasing pressure. However, the relationship between viscosity and these factors can be complex and is subject to further research.
Applications
Dynamic viscosity is a critical parameter in many engineering and scientific applications. It plays a key role in the design and operation of equipment and systems involving fluid flow, such as pumps, pipes, and turbines. It is also important in the study of fluid dynamics, lubrication theory, and material science.
See Also
