Hydraulic Diameter

Compute Dh and Re for non-circular ducts from flow area and wetted perimeter.

visual calculatorInternal Flow & Losses

Read the flow shape before trusting the number.

This page turns a CFD setup into regime, scale, and dominant-effect cues. Adjust the calculator below and compare the moving graphic with the computed result.

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hydraulic diameterduct flowReynolds

formula

KaTeX rendered

\begin{aligned}\text{D\_h = 4 A / P\_w}\\[0.35em]\text{Re\_Dh = rho U D\_h / mu}\end{aligned}

ASCII source

D_h = 4 A / P_w, Re_Dh = rho U D_h / mu

flow area A (m^2)wetted perimeter P (m)rho (kg/m^3)mu (Pa s)bulk velocity U (m/s)

D_h (m)

0.1333

Re_Dh

1.996e+5

D_h = 4A/P lets non-circular ducts use pipe-style Reynolds and pressure-loss estimates.

hydraulic diameter duct flow Reynolds