Free Hydraulic Diameter Calculator
Compute the hydraulic diameter of a rectangular duct or non-circular conduit for fluid flow analysis.
mm
mm
Hydraulic Diameter
342.9 mm
Cross-Sectional Area120,000 mm^2
Wetted Perimeter1,400 mm
Hydraulic Diameter vs Duct Width (a)
Hydraulic Diameter
The hydraulic diameter allows non-circular conduits to be analysed using the same formulas developed for circular pipes.
Formula
D_h = 4 A / P
where A is the cross-sectional flow area and P is the wetted perimeter. For a rectangular duct with sides a and b: D_h = 4ab / (2(a+b)) = 2ab / (a+b). For a circle, D_h equals the actual diameter.
Example Calculation
A rectangular HVAC duct 400 mm wide and 300 mm tall.
- 01Area = 400 x 300 = 120,000 mm^2
- 02Perimeter = 2 x (400 + 300) = 1,400 mm
- 03D_h = 4 x 120,000 / 1,400 = 342.9 mm
Frequently Asked Questions
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