hydraulic diameter

Hydraulic diameter is mainly used for calculations involving turbulent flow.

Hydraulic diameter is also used in calculation of heat transfer in internal flow problems.

The hydraulic radius is not half the hydraulic diameter as the name may suggest.

Microchannel in microtechnology is a channel with a hydraulic diameter below 1 mm.

The values depend on the hydraulic diameter.

The hydraulic diameter, D, is a commonly used term when handling flow in noncircular tubes and channels.

The most typical such confinement are microchannels, which are channels with a hydraulic diameter below 1 mm.

This result is generalized to non-circular channels using the hydraulic diameter, allowing a transition Reynolds number to be calculated for other shapes of channel.

In open channels, the Darcy-Weisbach equation is valid using the hydraulic diameter as equivalent pipe diameter.

For a circular pipe, the hydraulic diameter is exactly equal to the inside pipe diameter, as can be shown mathematically.

Should the hydraulic diameter in forced convection be on the order of tens or hundreds of micrometres, an extremely high heat transfer coefficient should result.

Other terms in the differential equation are the heat capacity ratio, γ, the Fanning friction factor, f, and the hydraulic diameter, D:

For calculations involving flow in non-circular ducts, the hydraulic diameter can be substituted for the diameter of a circular duct, with reasonable accuracy.

The term wetted perimeter is common in Civil Engineering, Environmental Engineering and heat transfer applications; it is associated with the hydraulic diameter.

These passages are measured as the hydraulic diameter and are made smaller for gases having smaller maximum experimental safe gaps (MESG).

Where is the heat transfer coefficient, is the Nusselt number, is the thermal conductivity of the fluid and is the hydraulic diameter of the channel or duct.

As Reynolds number is proportional to hydraulic diameter, fluid flow in channels of small hydraulic diameter will predominantly be laminar in character.

To turn the relationship into a proportionality coefficient of dimensionless quantity we can divide by the hydraulic diameter of the pipe, D, which is also constant along the pipe.

For a fully filled duct or pipe whose cross section is a regular polygon, the hydraulic diameter is equivalent to the diameter of a circle inscribed within the wetted perimeter.

For shapes such as squares, rectangular or annular ducts where the height and width are comparable, the characteristical dimension for internal flow situations is taken to be the hydraulic diameter, , defined as:

This dimensionless coefficient will be a combination of geometric factors such as π, the Reynolds number and (outside the laminar regime) the relative roughness of the pipe (the ratio of the roughness height to the hydraulic diameter).