# Hydraulic diameter

### From CFD-Wiki

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==Coaxial circular tube== | ==Coaxial circular tube== | ||

- | For a coaxial circular tube with an inner diameter | + | For a coaxial circular tube with an inner diameter <math>d_i</math> and an outer diameter <math>d_o</math> the hydraulic diameter is: |

:<math>d_h = 4 \; \frac{\frac{\pi d_o^2}{4} - \frac{\pi d_i^2}{4}}{\pi d_o + \pi d_i} = d_o - d_i</math> | :<math>d_h = 4 \; \frac{\frac{\pi d_o^2}{4} - \frac{\pi d_i^2}{4}}{\pi d_o + \pi d_i} = d_o - d_i</math> |

## Revision as of 13:52, 24 March 2006

The hydraulic diameter, , is commonly used when dealing with non-circular pipes, holes or ducts.

The definition of the hydraulic diamater is:

## Circular pipe

For a circular pipe or hole the hydraulic diamater is:

Where d is the real diameter of the pipe. Hence, for circular pipes the hydraulic diameter is the same as the real diameter of the pipe.

## Rectangular tube

For a rectangular tube or hole with the width and the height the hydraulic diamter is:

## Coaxial circular tube

For a coaxial circular tube with an inner diameter and an outer diameter the hydraulic diameter is: