laminar flow Formula
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\( f \;=\; \dfrac{ 64 }{ Re }\) (Friction Factor) \( f \;=\; \dfrac{ 64 }{ f }\) |
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| Symbol | English | Metric |
| \( f \) = Friction Factor |
\( dimensionless \) | \( dimensionless \) |
| \( Re \) = Reynolds Number | \( dimensionless \) | \( dimensionless \) |
Friction factor, abbreviated as f, also called Moody friction factor or Darcy-Weibach friction factor, a dimensionless number, is used in fluid dynamics to quantify the frictional losses or resistance to flow in pipes or conduits. The friction factor is primarily used in the Darcy-Weisbach equation, which relates the pressure drop or head loss in a pipe to the flow rate, pipe diameter, and other parameters.
The friction factor depends on various factors, including the nature of the fluid, the roughness of the pipe wall, and the Reynolds Number. The Reynolds number is a dimensionless parameter that characterizes the flow regime, and it is defined as the ratio of inertial forces to viscous forces in the fluid.
Colebrook-White Equation (Turbulent Flow) |
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| \( \dfrac{1}{ \sqrt{f} } \;=\; - 2 \cdot log \left( \dfrac{ \epsilon }{ 3.7 \cdot d_h } + \dfrac{ 2.51 }{ Re \cdot \sqrt{ f } } \right) \) | ||
| Symbol | English | Metric |
| \( \epsilon \) (Greek symbol epsilon) = Absolute Roughness | \( in \) | \( mm \) |
| \( f \) = Friction Factor | \( dimensionless \) | \( dimensionless \) |
| \( d_h \) = Hydraulic Diameter | \( in \) | \( mm \) |
| \( Re \) = Reynolds Number | \( dimensionless \) | \( dimensionless \) |
The friction factor can be determined experimentally for different flow conditions or pipe geometries, but it is often estimated using empirical correlations or obtained from published charts and tables. For laminar flow, the friction factor is calculated using the Hagen-Poiseuille equation, while for turbulent flow, several empirical equations, such as the Colebrook-White equation or the Swamee-Jain equation, are commonly used to estimate the friction factor. Accurate determination of the friction factor is essential for assessing pressure losses, determining pipe sizing, and designing efficient piping systems. It is also used in various engineering applications, including hydraulic calculations, fluid distribution systems, and HVAC systems.
Friction Factor calculator
