Reynolds Number Calculator (for motion of a viscous fluid)

This calculator computes Reynolds number, which is the ratio of the inertia forces to the friction forces in flow. It is used to determine the transition from laminar flow to turbulent flow in pipes.  
CalculationInput﻿﻿Fluid density, ρ
:1,000kg/m3​
﻿
﻿﻿Mean velocity, u
:5.00m/s​
﻿
﻿﻿Characteristic length, l
:1.00m​
﻿
﻿﻿Dynamic viscosity, µ
:20.00kg/ms ​
﻿
Output﻿﻿Reynolds Number(Re)
:250.00​
﻿
﻿﻿Type of flow
:Laminar​
﻿
﻿
Re=ρ×u×lµRe=\dfrac{ρ\times u\times l}{µ}Re=µρ×u×l​
Where:
﻿﻿ρ
 is the fluid density, which is the mass contained in a unit volume ﻿(kg/m3)
﻿
﻿﻿u
 is the mean velocity of flow ﻿(m/s)
﻿
﻿﻿l
 is the characteristic linear length, such as the diameter of a pipe or the chord length of an airfoil ﻿(m)
﻿
﻿﻿μ
 is the kinematic viscosity, which is a fluid property that describes the fluid's resistance to flow under the influence of gravity ﻿(m2/s)
. A higher ﻿μ
 means the fluid will flow more slowly for a given applied force.
ExplanationA British engineer and physicist, Osborne Reynolds, demonstrated a parameter in 1883 that can determine the transition from laminar to turbulent flow in pipes. The following distinctions of flow can be made using the Reynolds Number.
﻿﻿Re<2000
 the flow in a pipe is laminar, which means it is streamlined and smooth with no eddies
﻿﻿Re>2000
 the flow is turbulent, which means it is unpredictable with swirling motions and eddies
﻿
﻿
Reynolds number is crucial in determining fluid behaviour in different scenarios.  In aerospace engineering, aircraft design can be based on Reynolds number. It helps to design more efficient and effective systems.
Related ResourcesReynolds Number Calculator
Bernoulli Mass Flow Rate Calculator
Froude Number Calculator: Open Channel Flow
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