Tidally induced jet in Koombana Bay, Western Australia

1985 ◽  
Vol 36 (4) ◽  
pp. 453 ◽  
Author(s):  
CJ Hearn ◽  
JR Hunter ◽  
J Imberger ◽  
Senden D Van
Keyword(s):  
Aspect Ratio ◽  
Coastal Waters ◽  
Buoyant Jet ◽  
Buoyant Jets ◽  
Low Aspect Ratio ◽  
Discharge Velocity ◽  
Alongshore Current ◽  
New Criterion ◽  
Shallow Coastal Waters ◽  
Axial Speed

A study is made of a coastal tidal jet, based on a field program together with numerical and analytical modelling of the tidal discharge and jet dynamics. A new criterion is demonstrated for bottom attachment of low-aspect-ratio buoyant jets. The slightly buoyant jet is attached to the seabed over the initial 2 km of its trajectory, which lies in shallow coastal waters of less than 10 m depth. The jet is about 200 m in width and so its ratio of depth to half-width (aspect ratio) is much lower than for previously reported bottom-attached jets. The longitudinal retardation of the axial speed of the jet is due to bottom friction and entrainment. The jet widens only slowly with distance along its trajectory because entrainment is limited to its sides and is compensated by bathymetric deepening. The jet attaches to the coastline by turning, without loss of speed, to move parallel to the shore. The coastal attachment width is found to be a simple function of the ratio of the jet discharge velocity to the speed of the prevailing alongshore current.

Influence of a Coflowing Ambient Stream on a Turbulent Axisymmetric Buoyant Jet

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
S. Habli ◽  
N. Mahjoub Said ◽  
H. Mahmoud ◽  
H. Mhiri ◽  
G. Le Palec ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Data ◽  
Algebraic Model ◽  
Numerical Results ◽  
Turbulence Structure ◽  
Mean Flow ◽  
Buoyant Jet ◽  
Buoyant Jets ◽  
Free Jet ◽  
Discharge Velocity

This paper reports numerical results on turbulent buoyant axisymmetric jets in a coflowing ambient stream. The objective of this study is to compare the performance of the Reynolds stress algebraic model (ASM) with that of the k-ε turbulence model in predicting the flow field. A finite difference method has been used to solve a system of coupled partial differential equations. A comparison has been carried out between the numerical results obtained in the present work and experimental and numerical data reported in the literature. It has been found that the two investigated models reasonably predict the mean flow properties of the flow field. Nevertheless, the ASM proves to be better than the k-ε method to predict the effects of buoyancy and the turbulence structure. It has been found that the increase of the coflow can slow the development of the jet to the state of similarity of mean characteristic profiles. A jet with a ratio of coflow velocity u¯∞ to jet discharge velocity u¯0 less than 0.05 has developed to closely approximate a free jet in a stagnant medium while a jet with higher u¯∞∕u¯0 ratio never reaches a similarity state. In buoyant jets, only a flow with u∝∕u0⩽0.05 reaches a similarity state. Buoyancy ensures that the similarity region begins at a distance closer to the nozzle exit than if the medium is stagnant.

Development of an Ion Beam Probe System for Potential Measurement in the Low Aspect-Ratio Torus Experiment Device

2012 ◽  
Vol 132 (7) ◽  
pp. 567-573
Author(s):  
Hitoshi Tanaka ◽  
Shota Omi ◽  
Jun Katsuma ◽  
Yurie Yamamoto ◽  
Masaki Uchida ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Ion Beam ◽  
Potential Measurement ◽  
Low Aspect Ratio ◽  
Probe System ◽  
Experiment Device

THE NUMBER AND QUALITATIVE CHARACTERISTICS OF FRY FISH IN SHALLOW COASTAL WATERS OF THE VOLGA IN THE SUMMER-AUTUMN PERIOD OF 2012

2017 ◽  
pp. 65-73
Author(s):  
Edward Vladimirovich Nikitin
Keyword(s):  
Fish Species ◽  
Coastal Waters ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Volga River ◽  
Commercial Fish ◽  
Autumn Period ◽  
Fish Juveniles ◽  
Qualitative Characteristics ◽  
Shallow Coastal Waters

Shallow coastal waters of the Volga river is a flooded feeding area for fish juveniles of nonmigratory fish species. There takes place annual downstream migration of fluvial anadromous fish species from spawning grounds of the Volga river to the Northern Caspian Sea. The most important factors determining the number and qualitative characteristics of fry fishes are the level of the Caspian Sea (currently having a tendency to the lowering), hydrological and thermal regimes of the Volga river. Researches were carried out in definite periods of time. In the summer-autumn period of 2012 fry fishes were presented by 19 species (13 of them were commercial species), which belonged to 9 families. The article gives data on all the commercial fish species. In the first decade of July the maximum number of fry fish was registered in the western part of the Volga outfall offshore - in box 247 (19.86 mln specimens/km2), in the eastern part - in box 142 (20.4 mln specimens/km2). The most populous were roach, red-eye, silver bream and bream; size-weight characteristics were better in the areas remoted from the Volga delta. In the third decade of July the quantitative indicators of fry fish on these areas decreased, size-weight characteristics greatly increased. In the second decade of October in the western part of the seaside there were registered increased pre-wintering concentrations of fish juveniles, their qualitative indicators increased, which is evidence to favorable feeding conditions in 2012.

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