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# Hydraulic Diameter of a Channel of Water

AndrewS.Hydraulic Diameter of a Channel of Water

The **Hydraulic Diameter of a Channel of Water** calculator computes the hydraulic diameter of a channel of water based on the width of the channel and the depth of the water.

**INSTRUCTIONS:** Choose units and enter the following:

- (
**a**) This is the depth of the water. - (
**b**) This is the width of the channel.

**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 Channel of Water is:

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

where:

- D
_{H}is the hydraulic diameter of a fully filled rectangular duct . - b is the width of the duct.
- a is the depth of the water.

Can also be used to find the Hydraulic Diameter of a partially filled rectangular duct.

For the limiting case of a very wide duct (i.e. a slot of width *b* where *b *> a), D_{H} = 4a.

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

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**Hydraulic Diameter of a Channel of Water**, is used in 1 calculator.

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