Dean Number
The Dean number (De) is a dimensionless parameter used in fluid mechanics to characterize the importance of centrifugal forces relative to viscous forces in a curved pipe or duct.
The Dean number is defined as the ratio of the average secondary flow velocity to the primary flow velocity.
Dean number is proportional to { (Re . centrifugal force) / (inertial force) } and is used in momentum transfer in general and flow in curved channels calculations in particular. It is normally defined in the following form
Where: | ||
D | = | Diameter |
L | = | Length |
mu | = | Viscosity |
R | = | Radius of curvature of bend |
rho | = | Density |
V | = | Velocity |
The Dean number helps characterize the strength of secondary flow patterns, such as Dean vortices, which develop in curved pipes due to the combined effects of centrifugal and viscous forces. A higher Dean number indicates a greater influence of curvature-induced secondary flows.
The Dean number is particularly relevant in the analysis of flows in curved pipes, bends, and meandering channels, as it provides insights into flow behavior, pressure drop, and heat transfer characteristics. It’s commonly used in the design and optimization of various engineering systems involving curved fluid conduits.
