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Journal articles on the topic 'Negatively buoyant'

Author: Grafiati

Published: 4 June 2021

Last updated: 13 February 2022

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1

PAPANICOLAOU, PANOS N., ILIAS G. PAPAKONSTANTIS, and GEORGE C. CHRISTODOULOU. "On the entrainment coefficient in negatively buoyant jets." Journal of Fluid Mechanics 614 (October 16, 2008): 447–70. http://dx.doi.org/10.1017/s0022112008003509.

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Integral models proposed to simulate positively buoyant jets are used to model jets with negative or reversing buoyancy issuing into a calm, homogeneous or density-stratified environment. On the basis of the self-similarity assumption, ‘top hat’ and Gaussian cross-sectional distributions are employed for concentration and velocity. The entrainment coefficient is considered to vary with the local Richardson number, between the asymptotic values for simple jets and plumes, estimated from earlier experiments in positively buoyant jets. Top-hat and Gaussian distribution models are employed in a wide range of experimental data on negatively buoyant jets, issuing vertically or at an angle into a calm homogeneous ambient, and on jets with reversing buoyancy, discharging into a calm, density-stratified fluid. It is found that geometrical characteristics such as the terminal (steady state) height of rise, the spreading elevation in stratified ambient and the distance to the point of impingement are considerably underestimated, resulting in lower dilution rates at the point of impingement, especially when the Gaussian formulation is applied. Reduction of the entrainment coefficient in the jet-like flow regime improves model predictions, indicating that the negative buoyancy reduces the entrainment in momentum-driven, negatively buoyant jets.

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2

Kikkert, G. A., M. J. Davidson, and R. I. Nokes. "Inclined Negatively Buoyant Discharges." Journal of Hydraulic Engineering 133, no. 5 (May 2007): 545–54. http://dx.doi.org/10.1061/(asce)0733-9429(2007)133:5(545).

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3

Marugán-Cruz, C., J. Rodríguez-Rodríguez, and C. Martínez-Bazán. "Negatively buoyant starting jets." Physics of Fluids 21, no. 11 (November 2009): 117101. http://dx.doi.org/10.1063/1.3253690.

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4

Marugán-Cruz, C., J. Rodríguez-Rodríguez, and C. Martínez-Bazán. "Formation regimes of vortex rings in negatively buoyant starting jets." Journal of Fluid Mechanics 716 (January 25, 2013): 470–86. http://dx.doi.org/10.1017/jfm.2012.554.

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AbstractThe formation of vortex rings in negatively buoyant starting jets has been studied numerically for different values of the Richardson number, $\mathit{Ri}$, covering the range of weak to moderate buoyancy effects ($0\leq \mathit{Ri}\leq 0. 20$). Two different regimes have been identified in the vortex formation and the transition between them takes place at $\mathit{Ri}\approx 0. 03$. The vorticity distribution inside the vortex ring after pinching off from the trailing stem as well as the total amount of circulation it encloses (characterized by the formation number, $F$) show different behaviours with the Richardson number in the two regimes. The differences are associated with the different mechanisms by which the head vortex absorbs the circulation injected by the starting jet. While secondary vortices are engulfed by the leading vortex before separating from the trailing jet in the weak buoyancy effects regime ($0\lt \mathit{Ri}\lt 0. 03$), this phenomenon is not observed in the moderate buoyancy effects regime ($0. 03\lt \mathit{Ri}\lt 0. 2$). Moreover it is shown that the formation number of a negatively buoyant vortex ring can be determined by considering that its dynamics are similar to that of a neutrally buoyant vortex but propagating with velocity corresponding to the negatively buoyant one. Based on this simple idea, a phenomenological model is presented to describe quantitatively the evolution of the formation number with the Richardson number, $F(\mathit{Ri})$, obtained numerically. In addition, the limitations of different vortex identification methods used to evaluate the vortex properties in buoyant flows are discussed.

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5

Adamsson, Åsa, and Lars Bergdahl. "Simulation of temperature influence on flow pattern and residence time in a detention tank." Hydrology Research 37, no. 1 (February 1, 2006): 53–68. http://dx.doi.org/10.2166/nh.2006.0005.

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Three-dimensional simulations were used to model how a temperature difference between the incoming water and tank water influences the flow pattern and residence time in a detention tank. Buoyant, neutrally buoyant and negatively buoyant incoming jets were simulated. The simulations were compared with measurements for neutrally buoyant jets in a large-scale model of a detention tank (13 × 9×1 m). The results show that a negatively buoyant jet gives slightly less effective volume, defined as the time when 50% of added tracer has passed the outlet divided by the nominal residence time, than a neutrally buoyant jet. The flow pattern for a negatively buoyant jet at low densimetric Froude numbers consists of a current that travels along the bottom towards the outlet and a counter current at the surface towards the inlet, while the neutrally buoyant jet excites a surface jet with two large eddies on each side of the jet. This implies that the short-circuiting will decrease when a negatively buoyant jet at low densimetric Froude number occurs in the tank. The difference between the flow pattern excited by a buoyant jet and a neutrally buoyant jet is small.

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6

Fragkou, Anastasia, and Panos Papanicolaou. "Positively and Negatively Round Turbulent Buoyant Jets into Homogeneous Calm Ambient." Proceedings 2, no. 11 (July 31, 2018): 572. http://dx.doi.org/10.3390/proceedings2110572.

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A mathematical model has been employed to determine the characteristics of Boussinesq round buoyant jets which are injected horizontally or at an angle to horizontal, into a homogeneous, calm ambient. The solution of a system of three conservation first order nonlinear differential equations was obtained with a 4th Runge-Kutta scheme, using an entrainment coefficient which is related to the local Richardson number of the flow. Two types of positively and negatively buoyant jets were investigated (i) those where the buoyancy is a function of salinity henceforth called saline jets, and (ii) those where the buoyancy is a function of the temperature difference between jet and ambient fluid, henceforth called thermal jets.

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7

BAINES, PETER G. "Two-dimensional plumes in stratified environments." Journal of Fluid Mechanics 471 (November 5, 2002): 315–37. http://dx.doi.org/10.1017/s0022112002002215.

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Laboratory experiments on the flow of negatively buoyant two-dimensional plumes adjacent to a wall in a density-stratified environment are described. The flow passes through several stages, from an inertial jet to a buoyant plume, to a neutrally buoyant jet, and then a negatively buoyant plume when it overshoots its equilibrium density. This fluid then ‘springs back’ and eventually occupies an intermediate range of heights. The flow is primarily characterized by the initial value of the buoyancy number, B0 = Q0N3/g′02, where Q0 is the initial volume flux per unit width, g′0 is the initial buoyancy and N is the buoyancy frequency of the environment. Scaled with the initial equilibrium depth D of the in flowing fluid, the maximum depth of penetration increases with B0, as does the width of the initial down flow, which is observed to increase very slowly with distance downward. Observations are made of the profiles of flow into and away from the plume as a function of height. Various properties of the flow are compared with predictions from the ‘standard’ two-dimensional entraining plume model, and this shows generally consistent agreement, although there are differences in magnitudes and in details. This flow constrasts with flows down gentle slopes into stratified environments, where two-way exchange of fluid occurs.

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8

Brusasca, G., M. G. Morselli, S. Alessio, D. Anfossi, and L. Briatore. "Hydraulic simulation of negatively buoyant plumes." Il Nuovo Cimento C 8, no. 3 (May 1985): 259–72. http://dx.doi.org/10.1007/bf02574712.

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9

Ferrari, Simone, Maria Grazia Badas, and Giorgio Querzoli. "An Investigation on the Effects of Different Stratifications on Negatively Buoyant Jets." EPJ Web of Conferences 180 (2018): 02025. http://dx.doi.org/10.1051/epjconf/201818002025.

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Negatively buoyant jets develop when fluids are released upwards into a lighter fluid or, vice versa, downwards into a heavier fluid. There are many engineering applications, such as the discharge, via submerged outfalls, of brine from desalination plants into the sea. Some concerns are raised about the potential negative environmental impacts of this discharge. The increase in salinity is the major cause for environmental impact, as it is very harmful to many marine species. The diffusers for brine discharge are typically inclined upwards, to increase the path before the brine reaches the sea bottom, as it tends to fall downwards driven by negative buoyancy. The negatively buoyant jet that develops conserves axisymmetry only when released vertically, so that it is not possible to use the well-known equations for axisymmetric jets. The main target of this paper is to investigate on a laboratory model the effects of different stratifications on the features of negatively buoyant jets. This has been done via a LIF (Light Induced Fluorescence) technique, testing various release angles on the horizontal and densimetric Froude numbers. Except for the initial stage, a different widening rate for the upper boundary and the lower boundary has been highlighted.

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10

Friedman, P. D., and J. Katz. "Rise Height for Negatively Buoyant Fountains and Depth of Penetration for Negatively Buoyant Jets Impinging an Interface." Journal of Fluids Engineering 122, no. 4 (June 22, 2000): 779–82. http://dx.doi.org/10.1115/1.1311786.

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A vertical jet or fountain, whose velocity is opposite to the direction of its buoyant force, reverses direction after reaching a maximum penetration depth. This penetration depth is measured from the jet exit or, if present, the location of the undisturbed interface. This paper shows that the penetration depth is only a function of a Richardson number divided by a jet spreading factor. If no interface is present, the spreading factor is one; otherwise the spreading factor is only a function of distance between the jet exit and the interface. As long as the jet is fully turbulent, the penetration depth is independent of Reynolds and Weber numbers. These trends are applicable to a broad range of fluid systems including air jets impacting liquids as well as miscible and immiscible liquid-liquid systems with only slight density differences. [S0098-2202(00)00304-7]

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11

Hurzeler, BE, GN Ivey, and J. Imberger. "Spreading model for a turbidity current with reversing buoyancy from a constant-volume release." Marine and Freshwater Research 46, no. 1 (1995): 393. http://dx.doi.org/10.1071/mf9950393.

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Particle-laden flows with buoyant interstitial fluid from constant-volume releases are often encountered in nature and industry. These currents are driven by the excess density of the suspended particles, and although the bulk suspension is negatively buoyant, the buoyant interstitial fluid of the suspension can be detrained through the top of the current. Detrainment of interstitial fluid at the upper interface of the current and settling of particles through the viscous sublayer at the bottom of the current are shown to reduce the current spreading rate to less than that predicted by an inertia-buoyancy balance. Simple relationships are developed for the spreading of such turbidity currents, and these relationships are tested against published laboratory data. These results are then compared with a two-dimensional numerical simulation of the current using a buoyancy-extended k - ε turbulence closure scheme.

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12

Papanicolaou, Panos N., and George C. Stamoulis. "Vertical Round Buoyant Jets and Fountains in a Linearly, Density-Stratified Fluid." Fluids 5, no. 4 (December 4, 2020): 232. http://dx.doi.org/10.3390/fluids5040232.

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Turbulent round buoyant jets and fountains issuing vertically into a linearly density-stratified calm ambient have been investigated in a series of laboratory experiments. The terminal (steady-state) height of rise and the mean elevation of subsequent horizontal spreading have been measured in positively buoyant jets (at source level), including pure momentum jets and plumes, as well in momentum-driven negatively buoyant jets (fountains). The results from experiments confirmed the asymptotic analysis that was based on dimensional arguments. The normalized terminal height and spreading elevation with respect to the elevation of injection of momentum-driven (positively) buoyant jets and fountains attained the same asymptotic values. The numerical results from the solution of entrainment equations, using an improved entrainment coefficient function, confirmed the results related to buoyancy dominant flows (plumes), while their predictions in momentum-driven flows were quite low if compared to measurements.

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13

Rooney, G. G. "Descent and spread of negatively buoyant thermals." Journal of Fluid Mechanics 780 (September 7, 2015): 457–79. http://dx.doi.org/10.1017/jfm.2015.484.

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Results are presented from a numerical and analytical study of negatively buoyant thermals. The numerical study consists of large-eddy simulations of thermal descent and spread. The thermals are initiated by a spherical perturbation in the homogeneous background potential temperature. Simulations covering various release heights, thermal radii and thermal buoyancies are carried out. The analysis involves matching similarity models of a thermal and an axisymmetric gravity current, hence describing the flow evolution in terms of the initial conditions and flow coefficients only. The simulations demonstrate that the flow transition through the impingement region is relatively smooth, the main flow adjustment being in the initial post-release phase of the thermal. Comparison of the simulations and the model enables determination of the coefficients, and validation of the similarity approach to predict the radial speed, reduced gravity and depth of the spreading flow on the ground. The predictions of reduced gravity and depth also depend on quantification of the increase in gravity-current volume due to entrainment, which is obtained from the simulations.

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14

Valizadeh, Alireza, Jason P. Antenucci, and Grant Griffith. "REGULAR WAVE EFFECTS ON NEGATIVELY BUOYANT JETS." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 13. http://dx.doi.org/10.9753/icce.v36v.waves.13.

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Seawater desalination is an increasingly important technology in the supply of potable water to municipal communities. Brine created by this process is typically released back to the ocean via a nearshore diffuser into a wave-exposed climate. Despite this, little work has been published on the effect of waves on negatively buoyant jets. In this paper we outline the literature on this topic and the results of a series of computational fluid dynamics (CFD) simulations that address the role of regular waves on negatively buoyant jets.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/0085wAVVybc

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15

Crowe, A. T., M. J. Davidson, and R. I. Nokes. "Velocity measurements in inclined negatively buoyant jets." Environmental Fluid Mechanics 16, no. 3 (November 19, 2015): 503–20. http://dx.doi.org/10.1007/s10652-015-9435-y.

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16

Papakonstantis, Ilias G., George C. Christodoulou, and Panos N. Papanicolaou. "Inclined negatively buoyant jets 1: geometrical characteristics." Journal of Hydraulic Research 49, no. 1 (February 2011): 3–12. http://dx.doi.org/10.1080/00221686.2010.537153.

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17

Papakonstantis, Ilias G., George C. Christodoulou, and Panos N. Papanicolaou. "Inclined negatively buoyant jets 2: concentration measurements." Journal of Hydraulic Research 49, no. 1 (February 2011): 13–22. http://dx.doi.org/10.1080/00221686.2010.542617.

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18

NAITOH, Takashi, and Fumiya AOKI. "Translational velocity of negatively buoyant vortex rings." Proceedings of the Fluids engineering conference 2019 (2019): OS3–37. http://dx.doi.org/10.1299/jsmefed.2019.os3-37.

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19

Addad, Y., S. Benhamadouche, and D. Laurence. "The negatively buoyant wall-jet: LES results." International Journal of Heat and Fluid Flow 25, no. 5 (October 2004): 795–808. http://dx.doi.org/10.1016/j.ijheatfluidflow.2004.05.008.

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20

Friedman, Peter D., Vidya D. Vadakoot, William J. Meyer, and Steven Carey. "Instability threshold of a negatively buoyant fountain." Experiments in Fluids 42, no. 5 (March 15, 2007): 751–59. http://dx.doi.org/10.1007/s00348-007-0283-5.

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21

Clarke, A., M. R. Clarke, Lesley J. Holmes, and T. D. Waters. "Calorific Values and Elemental Analysis of Eleven Species of Oceanic Squids (Mollusca:Cephalopoda)." Journal of the Marine Biological Association of the United Kingdom 65, no. 4 (November 1985): 983–86. http://dx.doi.org/10.1017/s0025315400019457.

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INTRODUCTIONCephalopods may be divided into five types according to their buoyancy. Members of several families such as the Octopodidae, Loliginidae and Ommastrephidae are negatively buoyant and must swim to stay in midwater and are therefore highly muscular animals. Others have mechanisms to make them neutrally buoyant so they can remain suspended in midwater without effort. Nautilus, Spirula and cuttlefishes have low pressure gas-filled chambers and their flesh is muscular and non-buoyant (Denton & Gilpin-Brown, 1973). Squids of one family, the Gonatidae, have a low density oil in their livers to give buoyancy but most of their body is muscular. Some oceanic octopods have very watery tissues in which lighter chloride ions replace sulphate ions (Denton & Shaw, 1961). In 12 of the 26 teuthoid families the buoyancy is provided by low-density ammonia-rich solution in their body and head tissues or in an expanded coelomic cavity (Clarke, Denton & Gilpin-Brown, 1979). These ammoniacal squids are extremely abundant in the oceans of the world and form a large part of the diet of birds, cetaceans, seals and fish (Clarke, 1977). When their biomass is estimated from their utilization by predators it is important to know their properties as food and, in particular, their calorific values. As pointed out by Croxall & Prince in a review of the calorific values of cephalopods (1982), all the known values are of muscular, negatively buoyant species because they are of value as food for humans but no measurements have been made on the ammoniacal or oily species which are probably as important, or even more important, in the economy of the ocean (Clarke, 1983).

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22

Azim, M. A. "Isothermal free jets in high-temperature surroundings." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 8 (May 16, 2011): 1913–18. http://dx.doi.org/10.1177/0954406211401488.

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Two types of isothermal free jets, named positively and negatively buoyant, have been studied numerically to discern the effect of surrounding temperatures on their flow dynamics. Turbulence closure in those jets was achieved by standard k - ε model. The governing equations were solved using Implicit θ-Scheme and Tridiagonal Matrix Algorithm. Calculations were made for the jets having constant temperature at 20 °C and by varying surrounding temperatures from 20°C to 1000°C. It is clear that negatively buoyant jets but not the positively buoyant jets are nearly invariant to the change in surrounding temperatures compared to non-buoyant jet. Change in fluid dynamical behaviour of positively buoyant jets due to surrounding temperature change seems promising as it may offer the advantages of fuel jets in high-temperature air combustion.

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23

Stephenson, Richard. "The contributions of body tissues, respiratory system, and plumage to buoyancy in waterfowl." Canadian Journal of Zoology 71, no. 8 (August 1, 1993): 1521–29. http://dx.doi.org/10.1139/z93-215.

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This study examines buoyancy partitioning between body compartments in diving and surface-feeding Anatidae. Body tissue and plumage densities and the volumes of air in the respiratory system and plumage were analyzed using cadavers and restrained live specimens of waterfowl. The densities of the skeleton and remiges of surface feeders were significantly lower than those of divers but the differences were not sufficient to significantly reduce the body tissue density and buoyant force of divers. There were no other statistically significant differences in the body tissue densities of diving and surface-feeding waterfowl. The densities of contour feathers, down, and remiges were markedly different from each other but the net buoyant force of the feathers was less than 5% of that caused by the air trapped in the plumage layer. All cadavers were negatively buoyant in the absence of air in the respiratory system and plumage. Despite similar net buoyant forces, there were large differences in the volumes of air in the respiratory system and plumage between restrained ducks and cadavers. These results indicate that the use of cadavers or restrained ducks to determine net buoyancy, and hence power output, during voluntary foraging behaviour is unreliable.

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24

Bashitialshaaer, Raed, Magnus Larson, and Kenneth M. Persson. "An Experimental Investigation on Inclined Negatively Buoyant Jets." Water 4, no. 3 (September 24, 2012): 720–38. http://dx.doi.org/10.3390/w4030720.

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25

Bashitialshaaer, Raed, Magnus Larson, and Kenneth M. Persson. "An Experimental Investigation on Inclined Negatively Buoyant Jets." Water 4, no. 3 (September 24, 2012): 750–68. http://dx.doi.org/10.3390/w4030750.

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26

Friedman, P. D. "Oscillation in Height of a Negatively Buoyant Jet." Journal of Fluids Engineering 128, no. 4 (December 1, 2005): 880–82. http://dx.doi.org/10.1115/1.2201647.

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27

Sharma, Deepak, Suresh Singh Chauhan, Harlal Singh, and Amit Mukherjee. "Transient viscosities of negatively buoyant concentrated alumina suspensions." Asia-Pacific Journal of Chemical Engineering 11, no. 4 (March 28, 2016): 500–521. http://dx.doi.org/10.1002/apj.1971.

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28

Oliver, C. J., M. J. Davidson, and R. I. Nokes. "Removing the boundary influence on negatively buoyant jets." Environmental Fluid Mechanics 13, no. 6 (March 30, 2013): 625–48. http://dx.doi.org/10.1007/s10652-013-9278-3.

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29

Forge, Timothy B., and Derek R. Olson. "Scattering statistics of a negatively buoyant thermal plume." Journal of the Acoustical Society of America 146, no. 4 (October 2019): 3029. http://dx.doi.org/10.1121/1.5137501.

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30

Pantzlaff, L., and R. M. Lueptow. "Transient positively and negatively buoyant turbulent round jets." Experiments in Fluids 27, no. 2 (July 2, 1999): 117–25. http://dx.doi.org/10.1007/s003480050336.

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31

Kapoor, K., and Y. Jaluria. "Heat transfer from a negatively buoyant wall jet." International Journal of Heat and Mass Transfer 32, no. 4 (April 1989): 697–709. http://dx.doi.org/10.1016/0017-9310(89)90217-2.

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32

Seo, Il Won, and Chang Geun Song. "Dispersion of negatively buoyant effluent jetted from ORV." KSCE Journal of Civil Engineering 19, no. 4 (October 24, 2014): 1164–73. http://dx.doi.org/10.1007/s12205-013-0723-0.

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33

Lovvorn, James R., and David R. Jones. "Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.)." Canadian Journal of Zoology 69, no. 11 (November 1, 1991): 2879–87. http://dx.doi.org/10.1139/z91-406.

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Recent studies of diving ducks (Aythya spp.) have shown that buoyancy is far more important to locomotor costs of shallow diving than is hydrodynamic drag. Working with Canvasbacks (A. valisineria), Redheads (A. americana), and Lesser Scaup (A. afftnis), we investigated factors affecting buoyancy in models of locomotor energetics. Body volume can be accurately estimated from body mass (r2 = 0.82–0.95), but equations sometimes differ among species, and body volume relative to mass is higher in winter than in summer. Wing molt does not influence body volume or buoyancy. In scaup, an increase in body lipid from 35 to 190 g (from 5.4 to 22.3% of body mass) increases the energy costs of descent more through the inertial effects of higher mass and added mass of entrained water (82.8% of change) than through greater work against drag (12.0%) or buoyancy (5.2%). Costs of foraging at the bottom are 20% lower in the fatter birds because increased inertial resistance to the buoyant force is greater than the increase in buoyancy. Maximal changes in body lipid and associated hypertrophied muscle raise overall costs of diving to a depth of 2 m by only 2%. Such effects can be offset by altering respiratory and plumage air volumes (+ 15 mL for a 155-g lipid increase) or the relative amount of time spent at the bottom. Hence, diving energetics contrast with the energetics of flight, which are strongly affected by body mass changes. Reduced buoyancy from compression of air spaces with depth lowers costs of bottom foraging in scaup by 24% at 1.2 m and 36% at 2 m. Mass-specific plumage air volume decreases with increasing body mass (slope = 0.12), and body tissues are incompressible relative to air. Thus, buoyancy decreases faster with increasing pressure in smaller birds and they become negatively buoyant at shallower depths (about 43 m for Oldsquaws, Clangula hyemalis). Ducks such as eiders (Somateria spp.) weighing over 1200 g and diving to less than 60 m probably never become negatively buoyant.

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34

McConnochie, Craig D., Claudia Cenedese, and Jim N. McElwaine. "Surface Expression of a Wall Fountain: Application to Subglacial Discharge Plumes." Journal of Physical Oceanography 50, no. 5 (May 2020): 1245–63. http://dx.doi.org/10.1175/jpo-d-19-0213.1.

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AbstractWe use laboratory experiments and theoretical modeling to investigate the surface expression of a subglacial discharge plume, as occurs at many fjords around Greenland. The experiments consider a fountain that is released vertically into a homogeneous fluid, adjacent either to a vertical or a sloping wall, that then spreads horizontally at the free surface before sinking back to the bottom. We present a model that separates the fountain into two separate regions: a vertical fountain and a horizontal, negatively buoyant jet. The model is compared to laboratory experiments that are conducted over a range of volume fluxes, density differences, and ambient fluid depths. It is shown that the nondimensionalized length, width, and aspect ratio of the surface expression are dependent on the Froude number, calculated at the start of the negatively buoyant jet. The model is applied to observations of the surface expression from a Greenland subglacial discharge plume. In the case where the discharge plume reaches the surface with negative buoyancy the model can be used to estimate the discharge properties at the base of the glacier.

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35

MYRTROEEN, O. J., and G. R. HUNT. "Negatively buoyant projectiles – from weak fountains to heavy vortices." Journal of Fluid Mechanics 657 (July 1, 2010): 227–37. http://dx.doi.org/10.1017/s0022112010002508.

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An experimental investigation to establish the maximum rise height zm attained by a finite volume of fluid forced impulsively vertically upwards against its buoyancy into quiescent surroundings of uniform density is described. In the absence of a density contrast, the release propagates as a vortex ring and the vertical trajectory is limited by viscous effects. On increasing the source density of the release, gravitational effects limit the trajectory and a maximum rise height zm is reached. For these negatively buoyant releases, the dependence of zm on the length L of the column of ejected fluid, nozzle diameter D (= 2r0), dispensing time and source reduced gravity is determined by injecting saline solution into a fresh-water environment. For 3.4 ≲ L/D ≲ 9.0, zm/r0 is shown to scale on the source parameter η = Fr(L/D), a product of the source Froude number Fr and the aspect ratio L/D for the finite-volume release. Our results show that the morphology of the cap that develops above the source and the vortical motion induced within are sensitively dependent on the source conditions. Moreover, three rise-height regimes are identified: ‘weak-fountain-transition’, ‘vorticity-development’ and ‘forced-release’ regimes, each with a distinct morphology and dependence of dimensionless rise height on η.

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36

Ahmad, Nadeem, and Raouf E. Baddour. "Dilution and Penetration of Vertical Negatively Buoyant Thermal Jets." Journal of Hydraulic Engineering 138, no. 10 (October 2012): 850–57. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000588.

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37

Wang, Ruo-Qian, Adrian Wing-Keung Law, and E. Eric Adams. "Pinch-off and formation number of negatively buoyant jets." Physics of Fluids 23, no. 5 (May 2011): 052101. http://dx.doi.org/10.1063/1.3584133.

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38

Zhang, Hua, and Raouf E. Baddour. "Maximum Vertical Penetration of Plane Turbulent Negatively Buoyant Jets." Journal of Engineering Mechanics 123, no. 10 (October 1997): 973–77. http://dx.doi.org/10.1061/(asce)0733-9399(1997)123:10(973).

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West, Olivia R., Costas Tsouris, Sangyong Lee, Scott D. McCallum, and Liyuan Liang. "Negatively buoyant CO2-hydrate composite for ocean carbon sequestration." AIChE Journal 49, no. 1 (January 2003): 283–85. http://dx.doi.org/10.1002/aic.690490127.

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Ferrari, Simone, and Giorgio Querzoli. "Mixing and re-entrainment in a negatively buoyant jet." Journal of Hydraulic Research 48, no. 5 (October 2010): 632–40. http://dx.doi.org/10.1080/00221686.2010.512778.

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Christodoulou, G. C., I. G. Papakonstantis, and I. K. Nikiforakis. "Desalination brine disposal by means of negatively buoyant jets." Desalination and Water Treatment 53, no. 12 (July 4, 2014): 3208–13. http://dx.doi.org/10.1080/19443994.2014.933039.

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42

Henderson, Donald M. "Effects of stomach stones on the buoyancy and equilibrium of a floating crocodilian: a computational analysis." Canadian Journal of Zoology 81, no. 8 (August 1, 2003): 1346–57. http://dx.doi.org/10.1139/z03-122.

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A three-dimensional mathematical/computational model of the crocodilian Alligator mississippiensis has been developed to investigate the influence of gastroliths on crocodilian buoyancy. The model is self-correcting, recovers from large perturbations, and can replicate the body orientations and degrees of immersion seen in living crocodilians that have attained equilibrium with respect to the competing forces of buoyancy and weight. For a range of lung deflations where the model was still positively buoyant, adding gastroliths of mass equal to 1% of the body mass has the effect of lowering the body, on average, by 2.6% of the maximum trunk depth while simultaneously increasing the inclination of the body with its sagittal plane. With the lungs fully inflated, the model would become negatively buoyant only when loaded with stones weighing more than 6% of the total body mass. Without gastroliths the body would sink when the lungs were deflated by 40%50%. In all situations the model was resistant to capsizing. The relatively small amounts of gastroliths (<2% body mass) found in aquatic tetrapods are considered to be inconsequential for buoyancy and stability, and the lungs are the principle agent for hydrostatic buoyancy control.

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43

Adachi, Taiki, Jennifer L. Maresh, Patrick W. Robinson, Sarah H. Peterson, Daniel P. Costa, Yasuhiko Naito, Yuuki Y. Watanabe, and Akinori Takahashi. "The foraging benefits of being fat in a highly migratory marine mammal." Proceedings of the Royal Society B: Biological Sciences 281, no. 1797 (December 22, 2014): 20142120. http://dx.doi.org/10.1098/rspb.2014.2120.

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Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animal-borne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat.

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Elliott, Kyle H., Gail K. Davoren, and Anthony J. Gaston. "The influence of buoyancy and drag on the dive behaviour of an Arctic seabird, the Thick-billed Murre." Canadian Journal of Zoology 85, no. 3 (February 2007): 352–61. http://dx.doi.org/10.1139/z07-012.

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We used time–depth recorders to investigate the behaviour of free-ranging Thick-billed Murres ( Uria lomvia L., 1758) after attaching positively (n = 9), negatively (n = 10), or neutrally (n = 9) buoyant handicaps and increasing cross-sectional area by 3% (2.8 cm2; n = 8) or 6% (5.6 cm2; n = 6). When buoyancy was altered or drag increased, murres reduced dive depth and duration, suggesting that murres do not manipulate dive depth to obtain neutral buoyancy during the bottom phase. Ascent rate increased as the bird surfaced and mean ascent rate increased for deeper dives, presumably reflecting steeper dive angles and greater buoyancy during deep dives. For short dives (<150 s), preceding surface pauses were better correlated with dive depth and duration than succeeding surface pauses (surface pauses were “anticipatory”), suggesting that murres control inhalation rates based on anticipated dive depth and duration. Murres reduced ascent rate near the surface, possibly to reduce the risk of decompression sickness. Neutrally buoyant recorders attached to the legs had no effect on chick feeding frequencies or adult mass loss, suggesting that this attachment method may have the least effect on the foraging behaviour of alcids.

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Johnson, Thomas R., Gerard J. Farrell, Christopher R. Ellis, and Heinz G. Stefan. "Negatively Buoyant Flow in a Diverging Channel. I: Flow Regimes." Journal of Hydraulic Engineering 113, no. 6 (June 1987): 716–30. http://dx.doi.org/10.1061/(asce)0733-9429(1987)113:6(716).

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Stefan, Heinz G., and Thomas R. Johnson. "Negatively Buoyant Flow in Diverging Channel. III: Onset of Underflow." Journal of Hydraulic Engineering 115, no. 4 (April 1989): 423–36. http://dx.doi.org/10.1061/(asce)0733-9429(1989)115:4(423).

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Johnson, Thomas R., Christopher R. Ellis, and Heinz G. Stefan. "Negatively Buoyant Flow in Diverging Channel, IV: Entrainment and Dilution." Journal of Hydraulic Engineering 115, no. 4 (April 1989): 437–56. http://dx.doi.org/10.1061/(asce)0733-9429(1989)115:4(437).

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Kassem, Ahmed, Jasim Imran, and Jamil A. Khan. "Three-Dimensional Modeling of Negatively Buoyant Flow in Diverging Channels." Journal of Hydraulic Engineering 129, no. 12 (December 2003): 936–47. http://dx.doi.org/10.1061/(asce)0733-9429(2003)129:12(936).

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Philippe, P., C. Raufaste, P. Kurowski, and P. Petitjeans. "Penetration of a negatively buoyant jet in a miscible liquid." Physics of Fluids 17, no. 5 (May 2005): 053601. http://dx.doi.org/10.1063/1.1907735.

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O'Brien, Katherine R., Gregory N. Ivey, David P. Hamilton, Anya M. Waite, and Petra M. Visser. "Simple mixing criteria for the growth of negatively buoyant phytoplankton." Limnology and Oceanography 48, no. 3 (May 2003): 1326–37. http://dx.doi.org/10.4319/lo.2003.48.3.1326.

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