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Reynolds number

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Fluid dynamics index
Reynolds number diagram
The Reynolds number (Re) is caculated from the equation Re=VL/ν (where V is the average fluid velocity and ν is the kinematic viscosity), remembering that the dynamic viscosity μ=ν⋅ρ (where ρ is density).
Dynamic viscosity:
Kinematic viscosity:
Characteristic length:

Reynolds number:
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Enter either the dynamic viscosity and density, or the kinematic viscosity. The Reynolds number is proportional to the ratio of inertial to viscous effects. It relates to the amount of disorder in the flow, with a larger nunber (e.g. over ~2400 in a circular pipe) indicating turbulent flow. For calculation, the "characteristic length" should be taken according to convention. For example, in a pipe it is the hydraulic diameter, and in laminar flow over a plate, it is the plate length.