Environmental Engineering Reference
In-Depth Information
Hydraulic
Relating to the flow or conveyance of liquids, especially water through
pipes or channels.
Hydraulic jump
Abrupt, sudden change from supercritical to subcritical flow; flow transi-
tion from a rapid (supercritical flow) to a slow flow motion (subcritical
flow). Giorgio Bidone published the first investigations in 1820. The
present theory was developed by Bé1anger (1828) and has been verified
experimentally by many researchers (Bakhmeteff and Matzke 1936).
Hydraulic radius
Quotient of the wetted cross-sectional area and the wetted perimeter.
Hydrostatic pressure
Also known as the gravitational pressure, it is the pressure at a point due
to the weight of the fluid above it.
Ideal fluid
Frictionless and incompressible fluid; fluid has zero viscosity: it can't
sustain shear stress at any point.
=
International System of
Units
SI
Système International d'Unités; system of units adopted in 1960
based on the metre-kilogram-second (MKS) system. It is commonly
called the SI unit system. The basic seven units are: for length, mass, time,
electric current, luminous intensity, amount of substance and temperature.
Irregular waves
Waves with random wave periods (in practice also heights), which are
typical for natural wind-induced waves.
Karman constant
'Universal' constant of proportionality between the Prandl mixing length
and the distance from the boundary. Experimental results indicate that
κ
=
0.40.
Karman, von
Theodore von Karman (1881-1963) - Hungarian expert on fluid-dynamics,
who studied the vortex shedding behind a cylinder (Karman vortex street).
Kinematic viscosity
Dynamic viscosity divided by the fluid density.
Lagrange
Joseph-Louis
Lagrange
(1736-1813)
-
French
mathematician
and
astronomer.
Laminar flow
Flow characterized by fluid particles moving along smooth paths in thin
layers (laminas), with one layer gliding smoothly over an adjacent layer
and not influenced by adjacent layers perpendicular to the flow direction.
Laminar flows follow Newton's law of viscosity that relates shear stress to
the rate of angular deformation: τ
=
µ ( δv/δy ).
Level-top canal
A canal with horizontal embankments between cross-regulators to meet
zero flow condition for downstream control.
Longitudinal section
Vertical section along the centre line of a canal, it shows the original and
the final levels.
Main canal
Is the irrigation canal taking water from the supply (source) and conveying
the water to the lateral or secondary canals.
Maintenance
Operations performed in preserving irrigation or drainage canals and drain
pipes, hydraulic structures, service roads and works in good or near orig-
inal conditions. Repairs are part of maintenance; the regular, continuous
inspection and repair of irrigation and drainage systems.
Manning
Robert Manning (1816-1897); Chief Engineer of Public Works, Ireland.
In 1889, he presented two formulae, but he preferred to use the second
formula.
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