Merging of two or more plumes arranged around a circle

2016 ◽  
Vol 796 ◽  
pp. 712-731 ◽  
Author(s):  
G. G. Rooney
Keyword(s):  
Velocity Potential ◽  
Volume Flux ◽  
Horizontal Circle ◽  
Limiting Behaviour ◽  
Plume Flows

A model is presented of merging turbulent plumes from sources evenly spaced around a horizontal circle in a quiescent, unstratified background. This follows the previously developed method of (i) identifying the boundaries of interacting plumes with velocity-potential contours of line sinks and (ii) closing the generalised plume equations with an entrainment assumption based on the integrated flux across the plume boundaries. It includes the simplest case of two merging plumes, as well as being applicable to plume flows in restricted corner configurations. The model is shown to display the expected limiting behaviour for the source plumes and the merged plume. Consideration of the plume fluxes in the merging region leads to a revision of the entrainment assumption. The resulting revised model compares satisfactorily with previous estimates of volume flux in two merging plumes.

A technique for the direct measurement of volume flux of a plume

1983 ◽  
Vol 132 ◽  
pp. 247-256 ◽  
Author(s):  
W. Douglas Baines
Keyword(s):  
Direct Measurement ◽  
Vertical Cylinder ◽  
Industrial Building ◽  
Volume Flux ◽  
Mean Flow ◽  
Flow Through ◽  
Building Ventilation ◽  
Plume Flows ◽  
Total Discharge

It is observed that an interface is established in any open-ended vertical cylinder when a plume flows in the direction of a mean flow through the cylinder. The location of the interface defines the volume flux of the plume because the total discharge in the environment has been entrained at this level. Experiments have been conducted to verify this relation and to define the limits within which the interface is established. It is found that, as the buoyancy in the plume is reduced or the area of the environment is reduced, limits do exist. An application of the interface in industrial-building ventilation is described.

Computational studies of hard-body and 3-D effects in plume flows

1989 ◽  
Author(s):  
ETHIRAJ VENKATAPATHY ◽  
WILLIAM FEIEREISEN ◽  
SHIGERU OBAYASHI
Keyword(s):  
Computational Studies ◽  
Plume Flows

Observed seasonal regimes of North-South Atlantic Ocean interbasin exchange

2019 ◽  
Author(s):  
Hamed D. Ibrahim
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Volume Flux ◽  
The South ◽  
The North ◽  
Basin Scale ◽  
Interbasin Exchange ◽  
North And South

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

The Supersonic Flow Past a Slender Ducted Body of Revolution with an Annular Intake

1950 ◽  
Vol 1 (4) ◽  
pp. 305-318
Author(s):  
G. N. Ward
Keyword(s):  
Supersonic Flow ◽  
Velocity Potential ◽  
Operational Calculus ◽  
The Body ◽  
Body Of Revolution ◽  
Internal Flows ◽  
Flow Past ◽  
External Forces ◽  
Internal Pressures ◽  
Slender Body Of Revolution

SummaryThe approximate supersonic flow past a slender ducted body of revolution having an annular intake is determined by using the Heaviside operational calculus applied to the linearised equation for the velocity potential. It is assumed that the external and internal flows are independent. The pressures on the body are integrated to find the drag, lift and moment coefficients of the external forces. The lift and moment coefficients have the same values as for a slender body of revolution without an intake, but the formula for the drag has extra terms given in equations (32) and (56). Under extra assumptions, the lift force due to the internal pressures is estimated. The results are applicable to propulsive ducts working under the specified condition of no “ spill-over “ at the intake.

scholarly journals Local Dynamic Path Planning for an Ambulance Based on Driving Risk and Attraction Field

2021 ◽  
Vol 13 (6) ◽  
pp. 3194
Author(s):  
Fang Zong ◽  
Meng Zeng ◽  
Yang Cao ◽  
Yixuan Liu
Keyword(s):  
Path Planning ◽  
Potential Field ◽  
Velocity Potential ◽  
Attractive Potential ◽  
Local Dynamic ◽  
Repulsive Potential ◽  
Ambulance Personnel ◽  
Lane Changing ◽  
Dynamic Path Planning ◽  
Dynamic Path

Path planning is one of the most important aspects for ambulance driving. A local dynamic path planning method based on the potential field theory is presented in this paper. The potential field model includes two components—repulsive potential and attractive potential. Repulsive potential includes road potential, lane potential and obstacle potential. Considering the driving distinction between an ambulance and a regular vehicle, especially in congested traffic, an adaptive potential function for a lane line is constructed in association with traffic conditions. The attractive potential is constructed with target potential, lane-velocity potential and tailgating potential. The design of lane-velocity potential is to characterize the influence of velocity on other lanes so as to prevent unnecessary lane-changing behavior for the sake of time-efficiency. The results obtained from simulation demonstrate that the proposed method yields a good performance for ambulance driving in an urban area, which can provide support for designing an ambulance support system for the ambulance personnel and dispatcher.

Molecular sieving of small solutes by outer medullary descending vasa recta

1997 ◽  
Vol 272 (5) ◽  
pp. F579-F586 ◽  
Author(s):  
T. L. Pallone ◽  
M. R. Turner
Keyword(s):  
Water Channel ◽  
Fluorescein Isothiocyanate ◽  
Pressure Gradients ◽  
Volume Flux ◽  
Aquaporin 1 ◽  
A Value ◽  
Vasa Recta ◽  
Mathematical Simulations ◽  
Molecular Sieving ◽  
Hydrophilic Solutes

Molecular sieving of small solutes by outer medullary descending vasa recta (OMDVR). Descending vasa recta (DVR) plasma equilibrates with the medullary interstitium by volume efflux (Jv), as well as by influx of solutes. Jv is driven by transmural osmotic pressure gradients due to small hydrophilic solutes (delta pi s), NaCl and urea. DVR endothelium probably contains a "water-only" pathway most likely mediated by the aquaporin-1 (AQP1) water channel. We measured the ability of microperfused OMDVR to concentrate lumenal 22Na and [3H]raffinose when Jv was driven by transmural NaCl gradients. Collectate-to-perfusate ratios of 2 x 10(6) M(r) fluorescein isothiocyanate-labeled dextran volume marker (RDx), 22Na (RNa), and [3H]raffinose (Rraf) were measured in the absence and presence of Jv. During volume efflux (Jv > 0), RDx was 1.37 +/- 0.31. RNa increased from 0.64 +/- 0.03 when Jv = 0 to 0.82 +/- 0.05 when Jv > 0 and Rraf increased from 0.83 +/- 0.03 to 1.13 +/- 0.05: Mathematical simulations predict RNa and Rraf most accurately when the OMDVR reflection coefficient to the tracers is assigned a value near unity. This indicates that the OMDVR wall contains a pathway for osmotic volume flux that excludes small hydrophilic solutes, a behavior consistent with that of aquaporins.

Contracting ducts of finite length

1951 ◽  
Vol 2 (4) ◽  
pp. 254-271 ◽  
Author(s):  
L. G. Whitehead ◽  
L. Y. Wu ◽  
M. H. L. Waters
Keyword(s):  
Stream Function ◽  
Finite Length ◽  
Velocity Potential ◽  
Three Dimensional ◽  
Relaxation Method ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Hodograph Plane ◽  
Two Dimensional Flow ◽  
Working Section

SummmaryA method of design is given for wind tunnel contractions for two-dimensional flow and for flow with axial symmetry. The two-dimensional designs are based on a boundary chosen in the hodograph plane for which the flow is found by the method of images. The three-dimensional method uses the velocity potential and the stream function of the two-dimensional flow as independent variables and the equation for the three-dimensional stream function is solved approximately. The accuracy of the approximate method is checked by comparison with a solution obtained by Southwell's relaxation method.In both the two and the three-dimensional designs the curved wall is of finite length with parallel sections upstream and downstream. The effects of the parallel parts of the channel on the rise of pressure near the wall at the start of the contraction and on the velocity distribution across the working section can therefore be estimated.

scholarly journals Diffraction of plane elastic waves by a crack, with application to a problem of brittle fracture

1963 ◽  
Vol 3 (3) ◽  
pp. 325-339 ◽  
Author(s):  
M. Papadopoulos
Keyword(s):  
Elastic Waves ◽  
Scattered Field ◽  
Velocity Potential ◽  
Elastic Solid ◽  
Step Function ◽  
Free Surface Waves ◽  
Dependent Variables ◽  
Smooth Plane ◽  
New Feature ◽  
Set Up

AbstractA crack is assumed to be the union of two smooth plane surfaces of which various parts may be in contact, while the remainder will not. Such a crack in an isotropic elastic solid is an obstacle to the propagation of plane pulses of the scalar and vector velocity potential so that both reflected and diffracted fields will be set up. In spite of the non-linearity which is present because the state of the crack, and hence the conditions to be applied at the surfaces, is a function of the dependent variables, it is possible to separate incident step-function pulses into either those of a tensile or a compressive nature and the associated scattered field may then be calculated. One new feature which arises is that following the arrival of a tensile field which tends to open up the crack there is necessarily a scattered field which causes the crack to close itself with the velocity of free surface waves.

scholarly journals Limiting behaviour of the mean residual life

2003 ◽  
Vol 55 (1) ◽  
pp. 217-226 ◽  
Author(s):  
David M. Bradley ◽  
Ramesh C. Gupta
Keyword(s):  
Residual Life ◽  
Mean Residual Life ◽  
Limiting Behaviour ◽  
The Mean
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