scholarly journals PERIODIC FLOWS FROM TIDAL INLETS

1978 ◽  
Vol 1 (16) ◽  
pp. 78
Author(s):  
D.L. Wilkinson
Keyword(s):  
Bottom Topography ◽  
Vortex Pair ◽  
Periodic Flows ◽  
Variable Bottom ◽  
Dominant Feature ◽  
Coastal Inlet ◽  
Offshore Flow ◽  
Rotational Motions ◽  
Starting Jet ◽  
Coastal Inlets

A study was undertaken of the flow produced in the offshore region by tidal currents at the entrance of a coastal inlet. The gross features of the offshore flow structure were examined in an idealised two dimensional model in which a sinusoidally reversing flow was discharged from an open channel into a large stagnant basin. During each period of ebb flow, the discharge from the simulated inlet developed a structure very similar to that of a starting jet, and a vortex pair was observed to form and ultimately became the dominant feature of the flow. Although variable bottom topography and long shore currents will distort the flow pattern, the rotational motions observed in these experiments would be expected to persist. The study was restricted to coastal inlets in which the sectional area of the entrance channel is several orders of magnitude smaller the area of water surface inside the inlet.

scholarly journals Integral Constraints for Momentum and Energy in Zonal Flows with Parameterized Potential Vorticity Fluxes: Governing Parameters

2014 ◽  
Vol 44 (3) ◽  
pp. 922-943 ◽  
Author(s):  
V. O. Ivchenko ◽  
S. Danilov ◽  
B. Sinha ◽  
J. Schröter
Keyword(s):  
Ocean Circulation ◽  
Potential Vorticity ◽  
Channel Model ◽  
Bottom Topography ◽  
Flat Bottom ◽  
Zonal Flows ◽  
Integral Constraints ◽  
Variable Bottom ◽  
Eddy Fluxes ◽  
The Impact

Abstract Integral constraints for momentum and energy impose restrictions on parameterizations of eddy potential vorticity (PV) fluxes. The impact of these constraints is studied for a wind-forced quasigeostrophic two-layer zonal channel model with variable bottom topography. The presence of a small parameter, given by the ratio of Rossby radius to the width of the channel, makes it possible to find an analytical/asymptotic solution for the zonally and time-averaged flow, given diffusive parameterizations for the eddy PV fluxes. This solution, when substituted in the constraints, leads to nontrivial explicit restrictions on diffusivities. The system is characterized by four dimensionless governing parameters with a clear physical interpretation. The bottom form stress, the major term balancing the external force of wind stress, depends on the governing parameters and fundamentally modifies the restrictions compared to the flat bottom case. While the analytical solution bears an illustrative character, it helps to see certain nontrivial connections in the system that will be useful in the analysis of more complicated models of ocean circulation. A numerical solution supports the analytical study and confirms that the presence of topography strongly modifies the eddy fluxes.

scholarly journals Compressible starting jet: pinch-off and vortex ring–trailing jet interaction

2017 ◽  
Vol 817 ◽  
pp. 560-589 ◽  
Author(s):  
Juan José Peña Fernández ◽  
Jörn Sesterhenn
Keyword(s):  
Reynolds Number ◽  
Shear Layer ◽  
Vortex Ring ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Chamber Pressure ◽  
Vortex Interaction ◽  
Dominant Feature ◽  
Chamber Temperature ◽  
Starting Jet

The dominant feature of the compressible starting jet is the interaction between the emerging vortex ring and the trailing jet. There are two types of interaction: the shock–shear layer–vortex interaction and the shear layer–vortex interaction. The former is clearly not present in the incompressible case, since there are no shocks. The shear layer–vortex interaction has been reported in the literature in the incompressible case and it was found that compressibility reduces the critical Reynolds number for the interaction. Four governing parameters describe the compressible starting jet: the non-dimensional mass supply, the Reynolds number, the reservoir to unbounded chamber temperature ratio and the reservoir to unbounded chamber pressure ratio. The latter parameter does not exist in the incompressible case. For large Reynolds numbers, the vortex pinch-off takes place in a multiple way. We studied the compressible starting jet numerically and found that the interaction strongly links the vortex ring and the trailing jet. The shear layer–vortex interaction leads to a rapid breakdown of the head vortex ring when the flow impacted by the Kelvin–Helmholtz instabilities is ingested into the head vortex ring. The shock–shear layer–vortex interaction is similar to the noise generation mechanism of broadband shock noise in a continuously blowing jet and results in similar sound pressure amplitudes in the far field.

Best management practices for coastal inlets

Shore & Beach ◽  
2020 ◽  
pp. 75-83
Author(s):  
Nicole Elko ◽  
Kimberley McKenna ◽  
Tiffany Roberts Briggs ◽  
Nicholas Brown ◽  
Michael Walther ◽  
...  
Keyword(s):  
Best Management Practices ◽  
Management Practices ◽  
Cost Effective ◽  
Beach Erosion ◽  
Engineering Practice ◽  
Best Management ◽  
Conservation Measures ◽  
Coastal Inlet ◽  
Inlet Conditions ◽  
Coastal Inlets

Coastal inlets separate individual barrier islands or barrier spits and adjacent headlands (Hayes and Fitzgerald 2013). Inlets modify longshore transport and store sediment in flood and ebb shoals leading to dynamic adjacent shorelines. For example, 80% to 85% of the beach erosion in Florida can be attributed to inlets (Dean 1991). In some cases, structured inlets are designed to trap sand in a preferred location to minimize interference with navigation and facilitate its removal through dredging. Sound coastal engineering practice requires that this sand be placed on adjacent eroding beaches (NRC 1995) to protect coastal resources. This paper provides a brief overview of coastal inlet management and identifies Best Management Practices (BMPs) intended to balance human needs for inlet navigation with the natural systems adjacent to tidal inlets. Today’s conservation measures, which are a result of considerable monitoring, numerical modeling, and other science-based methods, demonstrate that BMPs improve management of sand resources and reduce impacts associated with tidal inlet dredging. For some inlet conditions, BMPs include use of inlet sediment sinks as cost-effective and eco-friendly sand sources for beach nourishment projects located close to the inlet. For optimal coastal inlet management, the ASBPA Science and Technology Committee recommends the following BMPs and conservation measures: • Limit frequency and duration of impacts, • Follow environmental windows, • Implement regional sediment management, • Use beach-compatible sand, • Conduct pre-, during-, and post-dredging monitoring, • Modify dredging equipment/practices, and • Design rechargeable, low-impact inlet borrow sites.

scholarly journals A Mathematical Model of Stratified Geophysical Fluid Flows Over Variable Bottom Topography

2020 ◽  
Vol 3 (3b) ◽  
pp. 112-137
Author(s):  
SI Iornumbe ◽  
T Tivde ◽  
RA Chia
Keyword(s):  
Mathematical Model ◽  
Shallow Water ◽  
Wave Motion ◽  
Wave Speed ◽  
Bottom Topography ◽  
Nonlinear Partial Differential Equations ◽  
Fluid Flows ◽  
Variable Bottom ◽  
Conservation Of Momentum ◽  
Model Equations

In this paper, a mathematical model of stratified geophysical fluid flow over variable bottom topography was derived for shallow water. The equations are derived from the principles of conservation of mass and conservation of momentum. The force acting on the fluid is gravity, represented by the gravitational constant. A system of six nonlinear partial differential equations was obtained as the model equations. The solutions of these models were obtained using perturbation method. The presence of the coriolis force in the shallow water equations were shown as the causes of the deflection of fluid parcels in the direction of wave motion and causes gravity waves to disperse. As water depth decreases due to varied bottom topography, the wave amplitude were shown to increase while the wavelength and wave speed decreases resulting in overturning of the wave. The results are presented graphically.

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