An investigation of induced free-surface wave oscillations in prismatic open-channel

ABSTRACT

This paper reported on the free-surface wave behavior in a rectangular open-channel, induced by sluice-gate maneuvers. Numerical computations used the McCormack scheme to solve the one-dimensional extended St-Venant model embedding the Prandtl power-law momentum correction coefficient. The fundamental pulsation of the hydraulic system was inspected using the analogy with the water-hammer theory, known in pressurized-pipe flows. Different flow scenarios were reported; including the superposition between (i) downstream water-hammer maneuver and sine excitation of upstream flow depth and (ii) sinusoidal fluctuations of upstream lateral inflow and downstream flow-depth. Results highlighted that such sluice-gates maneuvers involved severe scenarios leading to significant amplifications of the depth peak and crest values above the initial value.

KEYWORDS:

• Extended St-Venant model
• free-surface-wave
• McCormack scheme
• one-dimensional
• Prandtl power-law
• reflection
• wave

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notation

The following symbols are used in this paper :	=
A =	=	wetted cross-sectional area of the channel (m2)
T =	=	channel width (m)
c =	=	celerity (m/s)
Cr =	=	Courant number (-)
d =	=	flow depth measured perpendicular to the channel bed(m)
g =	=	acceleration due to gravity (m/s2)
l =	=	channel length (m)
m =	=	Manning roughness coefficient (s/m1/3)
q =	=	discharge (m3/s)
RH =	=	hydraulic radius(m)
s0 =	=	longitudinal slope of the channel bottom (m/m)
sf =	=	friction slope (m/m)
t =	=	time (s)
u =	=	depth-averaged velocity (m/s)
x =	=	abscissa measured along the channel bed (m)

Subscripts

0 = initial flow condition	=	(-)
i = mesh index in the x-direction	=	(-)
k = mesh index in the t-direction	=	(-)
N = number of grid points	=	(-)