§ DICTIONARY · CONCEPT
Laminar flow
Orderly flow in parallel layers, without mixing across them. Characteristic of low Reynolds number.
§ 01
Definition
In laminar flow, fluid moves in smooth parallel layers with negligible exchange between them. The velocity profile is steady, reversible, and predictable. In a straight pipe, laminar flow produces the parabolic Poiseuille profile, with zero velocity at the walls and maximum on the axis.
Laminar flow is the norm at low Reynolds number: thick syrup pouring, blood in capillaries, air over a slowly-flapping wing. Above the critical Re, small perturbations grow and the flow becomes turbulent.