PipeSageFlow regime thresholds
| Reynolds number | Regime | What it means |
|---|---|---|
| Re < 2,300 | Laminar | Smooth, layered flow. Friction factor = 64/Re. |
| 2,300 – 4,000 | Transitional | Unstable, unpredictable — avoid designing for this range. |
| Re > 4,000 | Turbulent | Chaotic mixing. Most real-world pipe flow falls here. Use Swamee-Jain or Colebrook. |
The Reynolds number is the ratio of inertial forces to viscous forces in a fluid. It's the single most important number in pipe flow analysis because it tells you which friction factor equation is valid — get the regime wrong and every downstream pressure drop or head loss calculation is wrong too.