Laminar flow

Laminar flow is fluid motion in smooth, orderly layers that slide past one another with little mixing. It contrasts with turbulent flow, where motion is irregular and strongly mixing.

Reynolds number: A dimensionless ratio of inertial to viscous forces used to characterize fluid-flow regimes. It helps predict whether a given flow will remain laminar or become turbulent.
Microfluidics: The science and technology of controlling small volumes of fluid in channels typically measured in micrometers. Small channel dimensions and low flow speeds often preserve layered motion.
Turbulence: A flow state with chaotic velocity fluctuations, vortices, and efficient mixing. Unlike laminar flow, turbulence continually transports momentum across the stream.
Couette flow: Viscous flow between parallel surfaces, driven by one surface moving relative to the other. It provides a simple model of adjacent layers sliding at different speeds.
Viscosity: A fluid’s resistance to deformation and flow, arising from internal friction. Viscous forces damp disturbances between neighboring layers.
Laminar flow hood: A ventilated enclosure that directs filtered air in a uniform stream across a work surface. Its controlled airflow limits airborne contamination around exposed materials.
Transition to turbulence: The process by which a flow changes from laminar motion to turbulence. It marks the boundary between the two flow regimes.
Poiseuille flow: Pressure-driven laminar flow through a channel, with a velocity profile set by geometry and viscosity. Its parabolic pipe-flow profile is a standard example of orderly layered motion.
No-slip condition: The boundary condition that a viscous fluid’s velocity matches a solid surface’s velocity at contact. It sets the slow-moving boundary layer that shapes laminar flow near walls.
Blood flow: The circulation of blood through the heart and blood vessels. Flow in many small vessels is approximately laminar, though pulsation and branching complicate it.

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