Two-layer hydraulic exchange flow through the Burlington Ship Canal

2010 ◽  
Vol 37 (12) ◽  
pp. 1631-1640
Author(s):  
A. Jalili ◽  
S. S. Li
Keyword(s):  
Field Data ◽  
Lower Layer ◽  
Lake Ontario ◽  
Exchange Flow ◽  
Volume Flux ◽  
Oscillation Modes ◽  
Harbour Water ◽  
Flow Through ◽  
Multiple Frequencies ◽  
Time Average

The exchange flow through the Burlington Ship Canal connecting Hamilton Harbour with Lake Ontario is investigated, using a two-layer internal hydraulics model. The summer exchange features an upper layer of polluted Harbour Water flowing from the harbour into the lake, whereas a lower layer of fresh Lake Ontario Water flowing from the lake into the harbour. We predict this exchange, taking into account the effects of both friction and barotropic forcing of multiple frequencies. Predictions of density interface and volume flux compare well with experimental and field data. The interface varies non-linearly with distance along the canal, with and without barotropic forcing. Our results indicate that the exchange flow is highly frictional. The barotropic forcing comprises oscillation modes of different frequency; these individual forcing modes cause the interface and layer velocities to fluctuate significantly in time, but their influence on the time average flows through the canal is minimal.

scholarly journals Two-Layer Rotating Exchange Flow between Two Deep Basins: Theory and Application to the Strait of Gibraltar

2005 ◽  
Vol 35 (9) ◽  
pp. 1568-1592 ◽  
Author(s):  
M-L. E. Timmermans ◽  
L. J. Pratt
Keyword(s):  
Exchange Rate ◽  
Space Shuttle ◽  
Lower Layer ◽  
Exchange Flow ◽  
Boundary Current ◽  
Strait Of Gibraltar ◽  
Flow Through ◽  
Upstream Flow ◽  
Key Parameter

Abstract Rotating two-layer exchange flow over a sill in a strait separating two relatively deep and wide basins is analyzed. Upstream of the sill in the deep upstream basin, the infinitely deep dense lower layer is assumed to be inactive, while the relatively thin upper layer flowing away from the sill forms a detached boundary current in the upstream basin. This analysis emphasizes the importance of this upstream boundary current, incorporating its width as a key parameter in a formalism for deducing the volume exchange rate and discriminating between maximal and submaximal states. Hence, even for narrow straits in which rotation does not dominate the dynamics within the strait, the importance of rotation in the wide upstream basin can be exploited. It is shown that the maximal allowable exchange transport through straits wider than 1½ Rossby deformation radii increases as rotation increases, unlike for smaller rotations, where the exchange decreases as rotation increases. The theory is applied to the exchange flow through the Strait of Gibraltar. This application illustrates how images of the oceans taken from space showing the width of the upstream flow, in this case a space shuttle photograph, might be used to determine the exchange transport through a strait. Maximal exchange conditions in the Strait of Gibraltar are predicted to apply at the time the space shuttle photograph was taken.

The role of dissipation and mixing in exchange flow through a contracting channel

2000 ◽  
Vol 407 ◽  
pp. 265-290 ◽  
Author(s):  
KRAIG B. WINTERS ◽  
HARVEY E. SEIM
Keyword(s):  
Numerical Model ◽  
Interfacial Layer ◽  
Large Scale ◽  
Lower Layer ◽  
Layer Structure ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Exchange Flow ◽  
Flow Through ◽  
Scale Turbulence

We investigate the transport of mass and momentum between layers in idealized exchange flow through a contracting channel. Lock-exchange initial value problems are run to approximately steady state using a three-dimensional, non-hydrostatic numerical model. The numerical model resolves the large-scale exchange flow and shear instabilities that form at the interface, parameterizing the effects of subgrid-scale turbulence. The closure scheme is based on an assumed steady, local balance of turbulent production and dissipation in a density-stratified fluid.The simulated flows are analysed using a two-layer decomposition and compared with predictions from two-layer hydraulic theory. Inter-layer transport leads to a systematic deviation of the simulated maximal exchange flows from predictions. Relative to predictions, the observed flows exhibit lower Froude numbers, larger transports and wider regions of subcritical flow in the contraction. To describe entrainment and mixing between layers, the computed solutions are decomposed into a three-layer structure, with two bounding layers separated by an interfacial layer of finite thickness and variable properties. Both bounding layers lose fluid to the interfacial layer which carries a significant fraction of the horizontal transport. Entrainment is greatest from the faster moving layer, occurring preferentially downstream of the contraction.Bottom friction exerts a drag on the lower layer, fundamentally altering the overall dynamics of the exchange. An example where bed friction leads to a submaximal exchange is discussed. The external forcing required to sustain a net transport is significantly less than predicted in the absence of bottom stresses.

A Combined CFD/MRV Study of Flow Through a Pin Bank

2014 ◽  
Author(s):  
Mike Siekman ◽  
David Helmer ◽  
Wontae Hwang ◽  
Gregory Laskowski ◽  
Ek Tsoon Tan ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Velocity Field ◽  
Turbulence Model ◽  
Field Data ◽  
Peak Velocity ◽  
Velocity Profiles ◽  
Mean Velocity ◽  
Magnetic Resonance Velocimetry ◽  
Sst Turbulence Model ◽  
Flow Through

RANS and time averaged URANS simulations of a pin bank are compared quantitatively and qualitatively to full 3D mean velocity field data obtained using magnetic resonance velocimetry (MRV). The ability of the CFD to match MRV velocity profiles through the pin bank is evaluated using the SST turbulence model. Quantitative comparisons of the velocity profiles showed an overprediction of peak velocity by the CFD at the first pin rows, and a smaller oscillatory error that diminishes as it moves through the pins, resulting in better matching towards the exit.

Multiple steady states in exchange flows across faults and the dissolution of

2015 ◽  
Vol 769 ◽  
pp. 229-241 ◽  
Author(s):  
Andrew W. Woods ◽  
Marc Hesse ◽  
Rachel Berkowitz ◽  
Kyung Won Chang
Keyword(s):  
Initial Conditions ◽  
Storage Systems ◽  
Exchange Flow ◽  
Cross Contamination ◽  
Volume Flux ◽  
Geological Storage ◽  
Deep Aquifer ◽  
Exchange Flows ◽  
Equilibrium Exchange ◽  
Different Levels

We develop a model of the steady exchange flows which may develop between two aquifers at different levels in the geological strata and across which there is an unstable density stratification, as a result of their connection through a series of fractures. We show that in general there are multiple steady exchange flows which can develop, depending on the initial conditions, and which may involve a net upwards or downwards volume flux. We also show that there is a family of equilibrium exchange flows with zero net volume flux, each characterised by a different interlayer flux of buoyancy. We present experiments which confirm our simplified model of the exchange flow. Such exchange flows may supply unsaturated water from a deep aquifer to drive dissolution of a structurally trapped pool of geologically stored $\text{CO}_{2}$, once the water in the aquifer containing the trapped pool of $\text{CO}_{2}$ has become saturated in $\text{CO}_{2}$, and hence relatively dense. Such exchange flows may also lead to cross-contamination of aquifer fluids, which may be of relevance in assessing risks of geological storage systems.

scholarly journals Estuarine Exchange Flow Is Related to Mixing through the Salinity Variance Budget

2018 ◽  
Vol 48 (6) ◽  
pp. 1375-1384 ◽  
Author(s):  
Parker MacCready ◽  
W. Rockwell Geyer ◽  
Hans Burchard
Keyword(s):  
Steady State ◽  
3D Model ◽  
Exchange Flow ◽  
Volume Flux ◽  
Estuarine Exchange ◽  
The Relationship ◽  
Total Exchange

AbstractThe relationship between net mixing and the estuarine exchange flow may be quantified using a salinity variance budget. Here “mixing” is defined as the rate of destruction of volume-integrated salinity variance, and the exchange flow is quantified using the total exchange flow. These concepts are explored using an idealized 3D model estuary. It is shown that in steady state (e.g., averaging over the spring–neap cycle) the volume-integrated mixing is approximately given by Mixing ≅ SinSoutQr, where Sin and Sout are the representative salinities of in- and outflowing layers at the mouth and Qr is the river volume flux. This relationship provides an extension of the familiar Knudsen relation, in which the exchange flow is diagnosed based on knowledge of these same three quantities, quantitatively linking mixing to the exchange flow.

Sign in / Sign up

Export Citation Format

Share Document