Effect of the opening aspect ratio on a buoyant pulsating exchange flow through a circular ceiling opening in a horizontal partition

2012 ◽  
Vol 41 (8) ◽  
pp. 666-680 ◽  
Author(s):  
B. Gera ◽  
P.K. Sharma ◽  
R.K. Singh
Keyword(s):  
Aspect Ratio ◽  
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.

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

Effect of aspect ratio on flow through and around a porous disk

2021 ◽  
Vol 6 (7) ◽  
Author(s):  
Tingting Tang ◽  
Jin Xie ◽  
Shimin Yu ◽  
Jianhui Li ◽  
Peng Yu
Keyword(s):  
Aspect Ratio ◽  
Porous Disk ◽  
Flow Through

Semi-empirical pressure loss model for viscous flow through high aspect ratio rectangular orifices

2019 ◽  
Vol 31 (7) ◽  
pp. 073603
Author(s):  
Yishak Yusuf ◽  
Reza Sabbagh ◽  
David S. Nobes
Keyword(s):  
Aspect Ratio ◽  
Viscous Flow ◽  
High Aspect Ratio ◽  
Pressure Loss ◽  
Loss Model ◽  
Flow Through ◽  
Semi Empirical

scholarly journals Flow through a helical pipe with rectangular cross-section

1970 ◽  
Vol 4 (2) ◽  
pp. 99-110
Author(s):  
Md Mahmud Alam ◽  
Delowara Begum ◽  
K Yamamoto
Keyword(s):  
Aspect Ratio ◽  
Iterative Method ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Main Tool ◽  
Numerical Approach ◽  
Dean Number ◽  
Helical Pipe ◽  
Flow Through ◽  
Marine Engineering

The effects of torsion, aspect ratio and curvature on the flow in a helical pipe of rectangular cross- section are studied by introducing a non-orthogonal helical coordinate system. Spectral method is applied as main tool for numerical approach where Chebyshev polynomial is used. The numerical calculations are obtained by the iterative method. The calculations are carried out for 0≤ δ ≤0.02, 1≤ λ ≤ 2.85, 1≤ γ ≤2.4, at Dn = 50 & 100 respectively, where d is the non-dimensional curvature, l the torsion parameter, g the aspect ratio and  Dn the pressure driven parameter (Dean number).DOI: http://dx.doi.org/10.3329/jname.v4i2.991 Journal of Naval Architecture and Marine Engineering Vol.4(2) 2007 p.99-110

Slip Flow in Eccentric Annuli

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
R. S. Alassar
Keyword(s):  
Aspect Ratio ◽  
Average Velocity ◽  
Slip Flow ◽  
Small Aspect Ratio ◽  
Channel Geometry ◽  
Bipolar Coordinates ◽  
Cylindrical Annulus ◽  
Velocity Flow ◽  
Flow Through ◽  
Eccentric Annuli

A solution of the problem of Poiseuille slip flow through an eccentric cylindrical annulus is obtained in bipolar coordinates. The solution is in excellent agreement with the two published limiting cases of slip flow through concentric annuli and no-slip flow through eccentric annuli. It is shown that for a fixed aspect ratio, fully eccentric channels sustain the maximum average velocity (flow rate) under the same pressure gradient and slip conditions. For a given channel geometry, the average velocity varies linearly with Knudsen number except for small aspect ratio. It is also shown that the extrema of the friction factor Reynolds number product is determined by how this product is defined or scaled.

Fluid Mechanics of Flow Through Rectangular Hydrophobic Microchannels

2011 ◽  
Author(s):  
Navid Kashaninejad ◽  
Weng Kong Chan ◽  
Nam-Trung Nguyen
Keyword(s):  
Aspect Ratio ◽  
Rectangular Cross Section ◽  
Expansion Method ◽  
Channel Height ◽  
Parallel Plates ◽  
Laminar Regime ◽  
Dimensional Solution ◽  
Eigenfunction Expansion Method ◽  
Flow Through ◽  
Liquid Flows

In this study, the effect of two important parameters have been evaluated for pressure driven liquid flows in microchannel in laminar regime by analytical modeling, followed by experimental measurement. These parameters are wettability conditions of microchannel surfaces and aspect ratio of rectangular microchannels. For small values of aspect ratio, the channel was considered to have a rectangular cross-section, instead of being two parallel plates. Novel expressions for these kinds of channels were derived using eigenfunction expansion method. The obtained two-dimensional solutions based on dual finite series were then extended to the case of a constant slip velocity at the bottom wall. In addition, for large values of aspect ratio, a general equation was obtained which is capable of accounting for different values of slip lengths for both upper and lower channel walls. Firstly, it was found out that for low aspect ratio microchannels, the results obtained by analytical rectangular 2-D model agree well with the experimental measurements as compared to one dimensional solution. For high aspect ratio microchannels, both models predict the same trend. This finding indicates that using the conventional 1-D solution may not be accurate for the channels where the width is of the same order as the height. Secondly, experimental results showed that up to 2.5% and 16% drag reduction can be achieved for 1000 and 250 micron channel height, respectively. It can be concluded that increasing the surface wettability can reduce the pressure drop in laminar regime and the effect is more pronounced by decreasing the channel height.

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