The hydraulic diameter, DH, is a commonly used term when handling flow in noncircular tubes and channels. Using this term one can calculate many things in the same way as for a round tube. It is defined as
Hydraulic diameter is also used in calculation of heat transfer in internal flow problems.
List of hydraulic diameters
|Circular tube||For a circular tube the hydraulic diameter is simply the diameter of the tube.|
|Rectangular duct (fully filled)|
|Channel of water or partial filled rectangular duct||For the limiting case of a very wide duct, i.e. a slot of width a where a ≫ b, then DH = 2b|