Field note / closed-conduit hydraulics
Velocity sets the loss scale.
The velocity head V2/(2g) appears in both the distributed and local-loss terms. Increasing flow or reducing diameter can therefore increase losses quickly, even before the pipe length changes.
The friction factor needs a basis.
The Darcy friction factor depends on Reynolds number and relative roughness. CivilKit keeps it as an explicit input so the user can trace it to a Moody diagram, Colebrook calculation, test basis, or project specification rather than hiding an unverified assumption.
Friction and minor losses are different inputs.
- Friction head hf uses fL/D and represents the length of straight pipe.
- Minor head hm uses ΣK and represents local fittings, entrances, exits, and equipment.
- Pressure equivalent converts the combined head loss using the entered fluid density; it does not include static elevation.
What still needs a system check
Confirm the full pipe condition, fluid properties, flow regime, pipe roughness, fitting schedule, elevation profile, pump curve, minimum pressure, transient risk, and operating envelope separately.