hf=f(L/D)V²/2g gives head loss from friction.
Head loss h_f=f(L/D)(V²/2g) where f is the Darcy friction factor: 64/Re for laminar, Colebrook equation (or Swamee-Jain) for turbulent. Pressure drop ΔP=ρ g h_f. Roughness ε/D matters at high Re.
100 m of 100 mm pipe at 2 m/s with f=0.02 loses h_f=0.02×1000×0.204≈4.1 m of head, about 40 kPa.
The Darcy-Weisbach equation gives head loss from friction, and it is the standard tool for sizing pipes and pumps in engineering practice.
hf=f(L/D)V²/2g gives head loss from friction.
The Darcy-Weisbach equation gives head loss from friction, and it is the standard tool for sizing pipes and pumps in engineering practice.
A dimensionless number that depends on Reynolds number and relative roughness, obtained from the Moody chart or an explicit correlation.
Head is energy per unit weight of fluid, so dividing the loss by gravity gives a length that is easy to compare with pump heads.
Typical applications include calculating the head loss in a 500 m water main, checking the friction loss in a ventilation duct and estimating the power needed for a pump in a process plant.
Study "Pipe flow" first (topic 58 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Hydraulic diameter for non-circular ducts. f=0.02–0.03 typical. Hazen-Williams alternative.
100 m of 100 mm pipe at 2 m/s with f=0.02 loses h_f=0.02×1000×0.204≈4.1 m of head, about 40 kPa.
The next topic is "Moody chart", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 59 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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