Unsteady Buoyancy Exchange Flow Through a Horizontal Partition

1995 ◽  
Vol 117 (2) ◽  
pp. 515-520 ◽  
Author(s):  
M. Singhal ◽  
R. Kumar
Keyword(s):  
Exchange Flow ◽  
Flow Through ◽  
Horizontal Partition

Buoyancy-Driven Exchange Flow Through Small Openings in Horizontal Partitions

1988 ◽  
Vol 110 (4a) ◽  
pp. 885-893 ◽  
Author(s):  
M. Epstein
Keyword(s):  
Flow Rate ◽  
Countercurrent Flow ◽  
Exchange Flow ◽  
Flow Measurements ◽  
Rate Versus ◽  
Single Opening ◽  
Flow Through ◽  
Horizontal Partition ◽  
Flow Configurations ◽  
Universal Correlation

This paper describes an experimental study of the phenomenon of buoyancy-driven exchange (countercurrent) flow through openings in a horizontal partition. A density-driven exchange flow was obtained by using brine above the partition and fresh water below the partition. In the first part of the study, flow measurements were made with a single opening, for opening ratios L/D in the range 0.01 to 10.0, where L and D are the length of the opening (in the direction normal to the partition) and the diameter of the opening, respectively. Four different flow regimes are identified as L/D is increased through this range. As a result of the competition between two of these regimes, the exchange flow rate versus L/D relation exhibits a peak. The exchange flow rate was found, for all practical purposes, to be independent of viscosity, enabling a universal correlation between Froude number (dimensionless exchange flow rate) and L/D. The second part of the study was an experimental investigation of the same phenomenon, but with two openings in the horizontal partition. Two openings were observed to give rise to three different flow configurations involving both one-way and countercurrent flows within the openings.

Combined Natural Convection and Forced Flow Through Small Openings in a Horizontal Partition, With Special Reference to Flows in Multicompartment Enclosures

1989 ◽  
Vol 111 (4) ◽  
pp. 980-987 ◽  
Author(s):  
M. Epstein ◽  
M. A. Kenton
Keyword(s):  
Direct Application ◽  
Forced Flow ◽  
Theoretical Treatment ◽  
Exchange Flow ◽  
Exchange Flows ◽  
Toxic Gases ◽  
Buoyancy Driven Flows ◽  
Single Opening ◽  
Flow Through ◽  
Horizontal Partition

Estimates of the magnitude of buoyancy-driven exchange flows through openings in partitions that separate compartments are needed to assess the movement of toxic gases and smoke through buildings. An experiment using water and brine as a substitute for a light gas moving in a dense gas was designed to measure combined forced and buoyancy-driven exchange flow through a single opening in a horizontal partition. No theoretical treatment exists for this configuration. The same apparatus was used to determine the magnitude of the forced flow required to purge the opening of the oppositely directed buoyant component (i.e., the “flooding” limit). Finally, combined forced and buoyancy-driven flows in a multicompartment enclosure were measured. It has been demonstrated that the combined forced and buoyancy-generated flows in the multicompartment structure can be predicted by a direct application of the results of the study of exchange flow through a single opening.

Maximal two-layer exchange over a sill and through the combination of a sill and contraction with barotropic flow

1986 ◽  
Vol 164 ◽  
pp. 53-76 ◽  
Author(s):  
D. M. Farmer ◽  
L. Armi
Keyword(s):  
Surface Layer ◽  
Reverse Flow ◽  
Single Layer ◽  
The Other ◽  
Exchange Flow ◽  
Strait Of Gibraltar ◽  
Exchange Flows ◽  
Barotropic Flow ◽  
Flow Through ◽  
Layer Flow

The analysis of two-layer exchange flow through contractions with a barotropic component treated by Armi & Farmer (1986) is extended to include exchange flows over sills and through a combination of a sill and contraction. It is shown that exchange over a sill is fundamentally different from exchange through a contraction. Control at the sill crest acts primarily through the deeper layer into which the sill projects and only indirectly controls the surface layer. This asymmetry in the control results in asymmetrical flows. The interface depth above the crest is not one half the total depth, as assumed in other studies by analogy with flow through contractions, but is somewhat deeper; the maximal exchange rate is less than for flow through a contraction of equal depth. When both a sill and a contraction are present, the contraction influences control at the sill crest only if it lies between the sill and the source of denser water. The response to barotropic flow is also asymmetrical: the transition to single-layer flow occurs at much lower speeds for a barotropic component in one direction than the other.Results of the analysis are applied to exchange flow through the Strait of Gibraltar, which includes both a sill and a contraction. It is shown that maximal exchange conditions apply throughout part of the tidal cycle, and observations illustrate several of the analytical predictions for barotropic flows, including the formation of fronts, single-layer flow, submaximal exchange and reverse flow.

scholarly journals Buoyancy-driven Exchange Flow through Double Openings with Having Multi Flow Patterns.

1997 ◽  
Vol 63 (615) ◽  
pp. 3572-3579
Author(s):  
Daigo TSURU ◽  
Koji OKAMOTO ◽  
Haruki MADARAME ◽  
Motoo FUMIZAWA
Keyword(s):  
Flow Patterns ◽  
Exchange Flow ◽  
Flow Through

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.

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