Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

• the most efficient way to navigate the Engineering ToolBox!

# Laminar Flow - Friction Coefficients

## Calculate friction coefficients for laminar fluid flow.

The friction coefficient - or factor - of a fluid flow at laminar conditions can be calculated as

λ = 64 / Re

= 64 μ / (dh u ρ)

= 64 ν / (dh u)                          (1)

where

λ = friction coefficient (non-dimensional)

Re = Reynolds Number (non-dimensional)

μ = absolute (dynamic) viscosity  (Ns/m2, lbm/s ft)

dhhydraulic diameter (mm, ft)

u = mean velocity in flow (m/s, ft/s)

ρ = density of fluid (kg/m3, lbm/ft3  )

ν μ / ρkinematic viscosity (m2/s, ft2/s)

Equation (1) is only valid at laminar conditions where Reynolds Number is less than 2300. For turbulent conditions where Reynolds Number exceeds 4000 the Colebrook equation should be used to calculate the friction coefficient.

In practice laminar flow is only actual for viscous fluids - like crude oil, fuel oil and other oils.

The friction coefficient for laminar flow indicated in the Moody diagram (SI based):

## Related Topics

• Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time

## Search Engineering ToolBox

• the most efficient way to navigate the Engineering ToolBox!

## SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

## Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Temperature

oC
oF

Length

m
km
in
ft
yards
miles
naut miles

Area

m2
km2
in2
ft2
miles2
acres

Volume

m3
liters
in3
ft3
us gal

Weight

kgf
N
lbf

Velocity

m/s
km/h
ft/min
ft/s
mph
knots

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O

Flow

m3/s
m3/h
US gpm
cfm

11 26