Groyne

About: Groyne is a research topic. Over the lifetime, 397 publications have been published within this topic receiving 4549 citations. The topic is also known as: groin & Breakwater.

Resistance of submerged groynes

Abstract: Groynes are commonly used in the major rivers in the Netherlands. They confine the flow of the river to a main channel but also act as resistance element once submerged and in that way influence the stage discharge relationship of the river. Several formulas exist describing groynes as a drag resistance. Another possible way of determining their resistance is by using a weir formula and fitting the up and downstream water levels to the water level slope of the river. In this thesis a schematized model of the river Waal is set up and progressively expanded. At first seven different drag and weir formulas are compared. There is no consensus for resistance is between them. They are therefor compared to a 2DV computer model of flow over a highly submerged weir in the SWASH software package. Drag resistance, expressed as a function of water depth to groyne height ratio has the same scaling as two weir formulas though they do not match in absolute terms. A 2DH computer model is then used to determine the magnitude of the lateral turbulent momentum exchange between the main channel, groyne fields and flood plain. Finally a 3D computer model is used to determine groyne resistance and the distribution of discharge and momentum around the groyne. Treating groynes as weirs is found to be an acceptable assumption. The schematized model is used to simulate a high discharge of 13.550 m3 s-1. Groynes, when seen as a weir, would be responsible for a 36 cm water level increase. Lateral turbulent momentum exchange increases this by another 34 cm, while using the groyne resistance found in the 3D model added only another 7 cm.

Bathymetric evolution at a coastal inlet after channel-edge groyne emplacement: a case study from the Gippsland lakes, Victoria, Australia

Abstract: Digital capture and analyses of time-series (1941-2005) digital elevation models (DEMs), developed for the Gippsland Lakes artificial entrance area (situated in Victoria, Australia) from analogue hydrographic charts, allows the long-term bathymetric results of rubble training wall (or ‘groyne’) emplacement in the Reeves Channel to be examined. Reeves Channel form has progressively become sinuous, and extensive flood-tide delta shoaling areas have also developed since ‘groyne field’ installation. It is argued that deviance from original Reeves Channel groyne emplacement design (proposed by a Royal Commission report in 1927) may have contributed heavily to the time-series development of Reeves Channel sinuosity and floodtide delta accretion.

Flow control by pile-group groynes used for riverbank instability management

Abstract: Smooth reduction of velocity from the mainstream to the bank is a desirable attempt when using a groyne for riverbank protection purpose. This can be achieved by applying modifications to groyne permeability or layout. In this study, the effects of different pile-group groynes on the flow deceleration were investigated experimentally. Different aspects including pile density, arrangement, row spacing and effects on the long downstream were considered. The results show that the pile arrangement pattern is an important factor on the control of flow magnitude and pattern behind a pile-group groyne. A gradual and smooth velocity reduction from the mainstream to the bank can be obtained by changing the arrangement of piles in a pile-group groyne.

Perforated caisson vertical groyne

Abstract: The invention discloses a perforated caisson vertical groyne. The perforated caisson vertical groyne comprises a caisson and a breast wall, wherein separation walls or separation plates are arranged in the caisson to form multiple cells; a caisson hole is formed in a wave surface exterior wall at the upper part of the caisson; the cell behind the caisson hole serves as a wave eliminating chamber; sand is filled in the other cells of the caisson besides of the wave eliminating chamber; the wave eliminating chamber is provided with a top plate; the top plate is provided with multiple water inlets; the breast wall is arranged at the top of the top plate; an inclined surface is arranged on a wave side of the breast wall, and is provided with multiple water outlets; and the water outlets are communicated with the water inlets formed in the top plate through pipes. The perforated caisson vertical groyne uses self kinetic energy of waves to eliminate the energy, reduces the wave force thereof, reduces the groyne back wave height, reduces the wave overtopping rate, reduces the caisson size, reduces the work amount, saves investments, is convenient to construct, can fully use self kinetic energy of water, saves the energy, and protects the environment.

Application of vof technique to channel improvement for panjiatai shoal in the yellow river

Abstract: In this paper, Volume Of Fluid (VOF) technique is used to simulate the free surface and the flow field affected by the groynes in the experimental flume and the natural river.A series of flume experiments are carried out.According to the orientation of groynes, angles from the flow direction to the axis of the groyne used in the experiments are assorted into obtuse angle, right angle, and acute angle as well.For each arrangement option, flow conditions are classified as the submerged and the non-submerged one.Velocities and the water level affected by single groyne or double-groyne are measured.The calculated results are agreement well with the experimental data.Because of the high demands in the mesh quality and the computer capability, the VOF technique is seldom used to simulate the natural river.In this paper, the VOF technique is also used to simulate the Panjiatai Shoal of 2km long, one of the important improvement reaches in the Yellow River.Two improvement schemes are compared and analyzed, and the better one is recommended.