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P is the wetted perimeter of the cross-section. More intuitively, the hydraulic diameter can be understood as a function of the hydraulic radius R H, which is defined as the cross-sectional area of the channel divided by the wetted perimeter. Here, the wetted perimeter includes all surfaces acted upon by shear stress from the fluid. [3]
The wetted perimeter is the perimeter of the cross sectional area that is "wet". [1] The length of line of the intersection of channel wetted surface with a cross sectional plane normal to the flow direction.
This means the greater the hydraulic radius, the larger volume of water the channel can carry. Based on the 'constant shear stress at the boundary' assumption, [6] hydraulic radius is defined as the ratio of the channel's cross-sectional area of the flow to its wetted perimeter (the portion of the cross-section's perimeter that is "wet"):
where A is the cross-sectional area, and P is the wetted perimeter. The wetted perimeter for a channel is the total perimeter of all channel walls that are in contact with the flow. [10] This means that the length of the channel exposed to air is not included in the wetted perimeter.
The variations of Q/Q (full) and V/V (full) with H/D ratio is shown in figure(b).From the equation 5, maximum value of Q/Q (full) is found to be equal to 1.08 at H/D =0.94 which implies that maximum rate of discharge through a conduit is observed for a conduit partly full.
It uses a combination of the energy, momentum, and continuity equations to determine water depth with a given a friction slope (), channel slope (), channel geometry, and also a given flow rate. In practice, this technique is widely used through the computer program HEC-RAS , developed by the US Army Corps of Engineers Hydrologic Engineering ...
is the hydraulic radius, which is the cross-sectional area of flow divided by the wetted perimeter (for a wide channel this is approximately equal to the water depth) [m]; is Manning's coefficient [time/length 1/3]; and; is a constant; k = 1 when using SI units and k = 1.49 when using BG units.
Direct and indirect methods are two ways in which bed material can be measured. Direct measurement is done through the use of a physical trap, placing the device in contact with the bed, “allowing the sediment transported as bedload to accumulate (or be trapped) inside the sampler for a certain amount of time, after which the sampler is raised to the surface and the material is emptied and ...