Hydraulic Diameter of a Rectangular Duct (fully filled)

The Hydraulic Diameter of a fully filled Rectangular Duct calculator compute the hydraulic diameter of a fully filled rectangular duct based on its dimensions.

INSTRUCTIONS: Choose units and enter the following:

• (a) Width of Rectangular Duct
• (b) Height of Rectangular Duct

Hydraulic Diameter (D_H): The calculator returns the diameter in meters.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The formula for the Hydraulic Diameter of a Rectangular Duct (fully filled)  is:

`D_H = (4*a*b)/(2*(a+b))`

where:

• D_H is the hydraulic diameter of a fully filled rectangular duct .
• a is the width of the duct.
• b is the height of the duct.

A hydraulic diameter is useful for dimensionless quantities (e.g.  Reynolds number) which employ a single variable for flow analysis.

Hydraulic diameter is mainly used for calculations involving turbulent flow. Secondary flows can be observed in non-circular ducts as a result of turbulent shear stress in the turbulent flow. Hydraulic diameter is also used in calculation of heat transfer in internal-flow problems.

Hydraulic Diameter Calculators

• Hydraulic Diameter of a Circular Tube
• Hydraulic Diameter of an Annulus
• Hydraulic Diameter of a Square Duct
• Hydraulic Diameter of a Rectangular Duct
• Hydraulic Diameter of a Channel of Water