Civil & Environmental
Pipe Flow Lab
Why does a rougher, faster, longer pipe cost so much more to pump? Drag the velocity, diameter, length and wall roughness and the operating point moves across the Moody chart (friction factor vs Reynolds, log-log). Below Re ≈ 2300 the flow is laminar and friction follows the simple 64/Re line; above it the flow turns turbulent and the friction factor depends on the relative roughness (Swamee–Jain, the explicit Colebrook fit). The Darcy–Weisbach head loss h_f = f·(L/D)·v²/(2g) then scales with the velocity squared — which is exactly why doubling the flow speed roughly quadruples the pumping cost.
200k
Reynolds
Turbulent
Regime
0.0230
Friction f
4.68 m
Head loss
Below Re ≈ 2300 the flow is laminar and friction follows the simple 64/Re line; above it the flow turns turbulent and the friction factor depends on the wall roughness (the Moody curves). Head loss then scales with f·(L/D)·v² — which is why doubling the speed roughly quadruples the pumping cost.
How to use this simulation
Why does a rougher, faster, longer pipe cost so much more to pump? Drag the velocity, diameter, length and wall roughness and the operating point moves across the Moody chart (friction factor vs Reynolds, log-log). Below Re ≈ 2300 the flow is laminar and friction follows the simple 64/Re line; above it the flow turns turbulent and the friction factor depends on the relative roughness (Swamee–Jain, the explicit Colebrook fit). The Darcy–Weisbach head loss h_f = f·(L/D)·v²/(2g) then scales with the velocity squared — which is exactly why doubling the flow speed roughly quadruples the pumping cost.
Everything runs in your browser — no sign-up, no download. Change a value and the result updates instantly, so you can build a feel for how each input shapes the outcome. It pairs with Crameleon's practice exams and step sheets when you want to go from intuition to working the problems.