Review of literature on local scour under plane turbulent wall jets

Abstract

Stability of hydraulic structures is threatened by persistent scour downstream of the apron, which renders their foundations exposed. Jets issuing under the sluice gate are turbulent enough to cause significant scour. Extensive study of the jets is, therefore, necessary in order to understand the underlying hydraulics and provide remedial measures. In this paper, a comprehensive review of the investigations on local scour caused by wall jets is presented, including both the classical as well as the prevalent approach. Various aspects of the scour under wall jets have been explained, including the process of scouring, different parameters affecting the maximum scour depth, analysis of flow characteristics within the scour hole and on the apron, time variation of scour depth, rate of sediment removal, and scour depth estimation formulae.

Experimental study on the scour due to a water jet subjected to lateral confinement

“…Each curve can be divided into three stages: the short-term phase, where an intense extraction of sediment occurs in a short time span, followed by the development phase, where the scour process slows down, and, finally, the long-term phase, with Y 0 approaching an asymptotic mean value, Y ∞ . Earlier studies of bed scour caused by turbulent two-dimensional jets described such logarithmic dependence [17][18][19]. But, unlike those results, in the present configuration, the curves display a remarkable change at the critical value Q * = 7.5 l/min.…”

“…The scarcity of experimental data on the scour process in channels with a very high degree of lateral confinement is in contrast with a large amount of research work devoted to the scour caused by plane (AR ≫ 1) wall jets [16,17]. For a layer of non-cohesive sediments immediately downstream of a rectangular opening, b 0 , the variation of the scour dimensions with the logarithm of time was found to be linear, and the scour process eventually attains an asymptotic stage, after several hours [18].…”

Experimental study of the bed morphology downstream of a sluice gate

“…In case of L = 8 cm (conditions N.3 and N.4) the jet decelerates as it flows over the apron while a wall boundary layer develops, until it becomes fully developed. According to [7] a minimum length of 6 to 8 times the sluice gate opening is required to achieve fully developed flow. In the case of L = 8 cm, the corresponding apron's length is equal to 13.3 times the sluice gate opening, and hence the flow is considered to be developed.…”

“…Besides the prevision of the maximum scour (e.g. [7]) that allows the correct design of such structures, the dune evolution downstream can provide insights into the sediment transport mechanism [4]. An extensive bibliographic revue of the flow under a sluice gate and its influence on scour can be found in [5][6][7].…”

Scour around Spur Dike in Sand–Gravel Mixture Bed

“…Local scour is a well-defined term in river engineering and is described as the removal of sediment particles from the alluvial streams. It is recognized as the main reason for the failure of hydraulic structures [5][6][7][8]. Figure 1 shows an actual picture of the failure of a vertical spur dike in the river Gaula near Haldwani, Uttrakhand in India.…”