FLOW / 006
Hydraulic Diameter Calculator
Calculate the equivalent internal-flow length scale from cross-sectional area and wetted perimeter. Use standard shapes or enter a custom section directly.
A compact way to scale non-circular internal flows.
Hydraulic diameter is widely used when Reynolds number, friction factor or heat-transfer correlations are expressed using a characteristic diameter for a non-circular duct.
Use wetted perimeter only. In partially wetted or open-channel problems, the free surface is not part of the wetted perimeter.
Check the correlation. A correlation developed for round pipes may not transfer perfectly to strongly non-circular laminar flows.
Keep geometry definitions consistent. Use the same characteristic scale across Reynolds, friction and heat-transfer calculations when the correlation assumes it.
Use hydraulic diameter consistently across Reynolds number and pressure-drop comparisons.
A wrong characteristic length can shift Reynolds number, friction-factor interpretation and the expected pressure loss.