How is hydraulic mean depth or hydraulic radius calculated?

Hydraulic mean depth, also known as hydraulic radius, is a key concept in fluid mechanics and open channel flow. It is defined as the ratio of the cross-sectional area of flow to the wetted perimeter of the channel. This measurement helps in understanding how effectively a channel can carry water and the flow characteristics within it.

The correct choice reflects this fundamental definition: it indicates that hydraulic radius is calculated by dividing the cross-sectional area by the wetted perimeter. The term “expressed as D/4” relates to the specific context of circular conduits but does not alter the underlying principle that connects area and wetted perimeter. This calculation is vital for determining flow characteristics in various hydraulic applications, including the evaluation of flow rates and the design of drainage systems.

Understanding this definition allows professionals in plumbing design and fluid mechanics to accurately assess flow behavior in different channel shapes and sizes, facilitating efficient and effective design practices.