Reynolds Number
D1. Physical and chemical oceanography and marine meteorologyDefinition
Dimensionless ratio of inertial to viscous forces.
The Reynolds number Re = U L / nu is the dimensionless ratio of inertial to viscous forces, with U and L the velocity and length scales and nu the kinematic viscosity. Low Re means smooth laminar flow; high Re (the ocean and atmosphere routinely exceed 10^8) means fully turbulent flow. Because geophysical Re is enormous, molecular viscosity is negligible at large scales and turbulence parameterizations stand in for the unresolved cascade.