Laminar flow

The velocity profile associated with laminar flow resembles a deck of playing cards. This flow profile of a fluid in a pipe shows the fluid acting in layers that slide over one another.

Laminar flow (/ˈlæmɪnər/) is the property of fluid particles in fluid dynamics to follow smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing.[1] 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 eddies or swirls of fluids.[2] 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.[3] Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.

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 viscosity of the fluid: laminar flow or turbulent flow. 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 Reynolds number, 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 eddies or small packets of fluid particles, which result in lateral mixing.[2] In non-scientific terms, laminar flow is smooth, while turbulent flow is rough.

  1. ^ Streeter, V.L. (1951-1966) Fluid Mechanics, Section 3.3 (4th edition). McGraw-Hill
  2. ^ a b Geankoplis, Christie John (2003). Transport Processes and Separation Process Principles. Prentice Hall Professional Technical Reference. ISBN 978-0-13-101367-4. Archived from the original on 2015-05-01.
  3. ^ Noakes, Cath; Sleigh, Andrew (January 2009). "Real Fluids". An Introduction to Fluid Mechanics. University of Leeds. Archived from the original on 21 October 2010. Retrieved 23 November 2010.