Laminar flow

Laminar flow

Laminar flow, sometimes known as streamline flow, occurs when a fluid flows in parallel layers, with no disruption between the layers. In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion, low momentum convection, pressure and velocity independent from time. It is the opposite of turbulent flow. In nonscientific terms laminar flow is "smooth," while turbulent flow is "rough."

The dimensionless Reynolds number is an important parameter in the equations that describe whether flow conditions lead to laminar or turbulent flow. Reynolds numbers of less than 2000 are generally considered to be of a laminar type. When the Reynolds number is much less than 1, Creeping motion or Stokes flow occurs. This is an extreme case of laminar flow where viscous (friction) effects are much greater than inertial forces.

For example, consider the flow of air over an airplane wing. The boundary layer is a very thin sheet of air lying over the surface of the wing (and all other surfaces of the airplane). Because air has viscosity, this layer of air tends to adhere to the wing. As the wing moves forward through the air, the boundary layer at first flows smoothly over the streamlined shape of the airfoil. Here the flow is called "laminar" and the boundary layer is a laminar layer.

For a practical demonstration of laminar and non-laminar flow, one can observe the smoke rising off a cigarette in a place where there is no breeze. The smoke from the cigarette will rise vertically and smoothly for some distance (laminar flow) and then will start undulating into a turbulent, nonlaminar flow.


External links

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* Laminar flow in a pipe
* [http://www.hrs-spiratube.com/en/resources/comparison-of-laminar-and-turbulent-flow.aspx Comparison of laminar and turbulent flow]


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  • laminar flow — n. the regular, continuous, smooth movement of a fluid …   English World dictionary

  • laminar flow — Hydraul., Mech. the flow of a viscous fluid in which particles of the fluid move in parallel layers, each of which has a constant velocity but is in motion relative to its neighboring layers. [1945 50] * * * Fluid flow in which the fluid travels… …   Universalium

  • laminar flow — noun nonturbulent streamline flow in parallel layers (laminae) • Hypernyms: ↑streamline flow * * * noun : streamline flow in a viscous fluid near a solid boundary contrasted with turbulent flow * * * Hydraul., Mech. the flow of a viscous fluid in …   Useful english dictionary

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  • laminar flow —    Flow in which the head loss is proportional to the first power of the velocity [22]. Water flowing in a laminar manner will have streamlines that remain distinct and the flow direction at every point remains unchanged with time.    Synonymous… …   Lexicon of Cave and Karst Terminology

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