Abstract
Observations of turbulent convection in the environment are of variously sustained plume-like flows or intermittent thermal-like flows. At different times of the day the prevailing conditions may change and consequently the observed flow regimes may change. Understanding the link between these flows is of practical importance meteorologically, and here we focus our interest upon plume-like regimes that break up to form thermal-like regimes. It has been shown that when a plume rises from a boundary with low conductivity, such as arable land, the inability to maintain a rapid enough supply of buoyancy to the plume source can result in the turbulent base of the plume separating and rising away from the source. This plume ‘pinch-off’ marks the onset of the intermittent thermal-like behavior. The dynamics of turbulent plumes in a uniform environment are explored in order to investigate the phenomenon of plume pinch-off. The special case of a turbulent plume having its source completely removed, a ‘stopping plume’, is considered in particular. The effects of forcing a plume to pinch-off, by rapidly reducing the source buoyancy flux to zero, are shown experimentally. We release saline solution into a tank filled with fresh water generating downward propagating steady turbulent plumes. By rapidly closing the plume nozzle, the plumes are forced to pinch-off. The plumes are then observed to detach from the source and descend into the ambient. The unsteady buoyant region produced after pinch-off, cannot be described by the power-law behavior of either classical plumes or thermals, and so the terminology ‘stopping plume’ (analogous to a ‘starting plume’) is adopted for this type of flow. The propagation of the stopping plume is shown to be approximately linearly dependent on time, and we speculate therefore that the closure of the nozzle introduces some vorticity into the ambient, that may roll up to form a vortex ring dominating the dynamics of the base of a stopping plume.
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References
Ahrens CD (2000) Essentials of meteorology: an invitation to the atmosphere. Cengage Learning, Stamford
Backhaus JO, Kampf J (1999) Simulations of sub-mesoscale oceanic convection and ice–ocean interactions in the Greenland sea. Deep-Sea Res II 46:1427–1455
Bluth GJS, Shannon JM, Watson IM, Prata AJ, Realmuto VJ (2007) Development of an ultra-violet digital camera for volcanic \(\text{ SO }_{2}\) imaging. J Volcanol Geotherm Res 161:47–56
Castaing B, Gunaratne G, Heslot F, Kadanoff L, Libchaber A, Thomae S, Wu XZ, Zaleski S, Zanetti G (1989) Scaling of hard thermal turbulence in Rayleigh–Bénard convection. J Fluid Mech 204:1–30
Cetegen BM, Ahmed TA (1993) Experiments on the periodic instability of buoyant plumes and pool fires. Combust Flame 93:157–184
Cetegen BM, Kasper KD (1997) Experiments on the oscillatory behaviour of buoyant plumes of helium and helium–air mixtures. Phys Fluids 8:2974–2984
Cetegen BM (1997) Behavior of naturally unstable and periodically forced axisymmetric buoyant plumes of helium and helium–air mixtures. Phys Fluids 9:3742–3752
Dalziel SB (2012) DigiFlow. DL Research Partners. http://www.damtp.cam.ac.uk/lab/digiflow
Fraenkel LE (1970) On steady vortex rings of small cross-section in an ideal fluid. Proc R Soc A 316:29–62
Fraenkel LE (1972) Examples of steady vortex rings of small cross-section in an ideal fluid. J Fluid Mech 51:119–135
Grossmann S, Lohse D (2000) Scaling in thermal convection: a unifying theory. J Fluid Mech 407:27–56
Hill MJM (1894) On a spherical vortex. Phil Trans R Soc Lond A 185:231–245
Holland PR, Hewitt RE, Scase MM (2014) Wave breaking in dense plumes. J Phys Oceanogr 44:790–800
Hollerback R, Jones CA (1993) Influence of the earth’s inner core on geomagnetic fluctuations and reversals. Nature 365:541–543
Horsch GM, Stefan HG (1988) Convective circulation in littoral water due to surface cooling. Limnol Oceanogr 33:1068–1083
Howard LN (1964) Convection at high Rayleigh number. In: Gortler H (ed) Proceedings 11th international congress on applied mechanics. Springer, Munich, pp 1109–1115
Hübner J (2004) Buoyant plumes in a turbulent environment. PhD Thesis. University of Cambridge
Hunt GR, Kaye NB (2005) Lazy plumes. J Fluid Mech 533:329–338
Hunt GR, Linden PF (2001) Steady-state flows in an enclosure ventilated by buoyancy forces assisted by wind. J Fluid Mech 426:355–386
Hunt JCR (1998) Eddy dynamics and kinematics of convective turbulence. In: Plate EJ, Fedorovich E (eds) Buoyant convection in geophysical flows. Kluwer, Dordecht, pp 41–82
Hunt JCR, Kaimal JC, Gaynor JE (1988) Eddy structure in the convective boundary layer-new measurements and new concepts. Q J R Met Soc 114:827–858
Hunt JCR, Vrieling AJ, Nieuwstadt FTM, Fernando HJS (2003) The influence of the thermal diffusivity of the lower boundary on eddy motion in convection. J Fluid Mech 491:183–205
Lei C, Patterson JC (2002) Natural convection in a reservoir sidearm subject to solar radiation: experimental observations. Exp Fluids 32:590–599
Morton BR, Taylor GI, Turner JS (1956) Turbulent gravitational convection from maintained and instantaneous sources. Proc R Soc Lond A 234:1–32
Norbury J (1972) A family of steady vortex rings. J Fluid Mech 57:417–431
Papanicolaou PN, List EJ (1988) Investigations of round vertical turbulent buoyant jets. J Fluid Mech 195:341–391
Prata AJ, Bernardo C (2008) Retrieval of SO\(_{2}\) from a ground-based thermal infrared imaging camera. NILU internal report
Rose WI (1987) Volcanic activity at Santiaguito Volcano, 1976–1984. Spec Pap Geol Soc Am 212:101–111
Scase MM, Caulfield CP, Dalziel SB, Hunt JCR (2006) Time-dependent plumes and jets with decreasing source strengths. J Fluid Mech 563:443–461
Scase MM, Caulfield CP, Dalziel SB (2008) Temporal variation of non-ideal plumes with sudden reductions in buoyancy flux. J Fluid Mech 600:181–199
Scase MM (2009) Evolution of volcanic eruption columns. J Geophys Res 114:F04003
Scase MM, Hewitt RE (2012) Unsteady turbulent plume models. J Fluid Mech 697:455–480
Scorer RS (1954) The nature of convection as revealed by soaring birds and dragonflies. Q J R Met Soc 80:68–77
Scorer RS (1957) Experiments on convection of isolated masses of buoyant fluid. J Fluid Mech 2:583–594
Townsend AA (1959) Temperature fluctuations over a heated horizontal surface. J Fluid Mech 5:209–241
Turner JS (1962) The ‘starting plume’ in neutral surroundings. J Fluid Mech 13:356–368
Unger DR, Muzzio FJ (1999) Laser-induced fluorescence technique for the quantification of mixing in impinging jets. AIChE J 45:2477–2486
Uscinski BJ, Kaletsky A, Stanek CJ, Rouseff D (2003) An acoustic shadowgraph trial to detect convection in the arctic. Waves Random Media 13:107–123
Wang RQ, Law AWK, Adams EE, Fringer OB (2011) Large-eddy simulation of starting buoyant jets. Environ Fluid Mech 11:591–609
Witham F, Phillips JC (2008) The dynamics and mixing of turbulent plumes in a turbulently convecting environment. J Fluid Mech 602:39–61
Acknowledgments
AK acknowledges support from Engineering and Physical Sciences Research Council (EPSRC) studentship. AK and MMS would like to gratefully acknowledge the very constructive input of the Referees.
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Kattimeri, A., Scase, M.M. Turbulent ‘stopping plumes’ and plume pinch-off in uniform surroundings. Environ Fluid Mech 15, 923–937 (2015). https://doi.org/10.1007/s10652-014-9387-7
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DOI: https://doi.org/10.1007/s10652-014-9387-7