Laminar flow

Laminar flow is the property of fluid particles in <a href="/facts/Fluid_dynamics/y7uzSCfg">fluid dynamics</a> to follow smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another smoothly. There are no cross-currents perpendicular to the direction of flow, nor <a href="/facts/Eddies/V0hTLblX">eddies</a> or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface.
Laminar flow is a flow regime characterized by high <a href="/facts/Momentum_diffusion/LnpwMFtG">momentum diffusion</a> and low momentum <a href="/facts/Convection/E8vsCPhu">convection</a>.
When a fluid is flowing through a closed channel such as a pipe or between two flat plates, either of two types of flow may occur depending on the velocity and <a href="/facts/Viscosity/QLVfrdCz">viscosity</a> of the fluid: laminar flow or <a href="/facts/Turbulence/NpgFUhG5">turbulent flow</a>. Laminar flow occurs at lower velocities, below a threshold at which the flow becomes turbulent. The threshold velocity is determined by a dimensionless parameter characterizing the flow called the <a href="/facts/Reynolds_number/4sdungsf">Reynolds number</a>, which also depends on the viscosity and density of the fluid and dimensions of the channel. Turbulent flow is a less orderly flow regime that is characterized by <a href="/facts/Eddies/V0hTLblX">eddies</a> or small packets of fluid particles, which result in lateral mixing. In non-scientific terms, laminar flow is smooth, while turbulent flow is rough.

Laminar flow open-in-new

Laminar flow