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Layer formation in sedimentary fingering convection

  • J. F. Reali (a1), P. Garaud (a1), A. Alsinan (a2) and E. Meiburg (a2)
Abstract

When particles settle through a stable temperature or salinity gradient they can drive an instability known as sedimentary fingering convection. This phenomenon is thought to occur beneath sediment-rich river plumes in lakes and oceans, in the context of marine snow where decaying organic materials serve as the suspended particles or in the atmosphere in the presence of aerosols or volcanic ash. Laboratory experiments of Houk & Green (Deep-Sea Res., vol. 20, 1973, pp. 757–761) and Green (Sedimentology, vol. 34(2), 1987, pp. 319–331) have shown sedimentary fingering convection to be similar to the more commonly known thermohaline fingering convection in many ways. Here, we study the phenomenon using three-dimensional direct numerical simulations. We find evidence for layer formation in sedimentary fingering convection in regions of parameter space where it does not occur for non-sedimentary systems. This is due to two complementary effects. Sedimentation affects the turbulent fluxes and broadens the region of parameter space unstable to the $\unicode[STIX]{x1D6FE}$ -instability (Radko, J. Fluid Mech., vol. 497, 2003, pp. 365–380) to include systems at larger density ratios. It also gives rise to a new layering instability that exists in $\unicode[STIX]{x1D6FE}$ -stable regimes. The former is likely quite ubiquitous in geophysical systems for sufficiently large settling velocities, while the latter probably grows too slowly to be relevant, at least in the context of sediments in water.

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Corresponding author
Email address for correspondence: pgaraud@ucsc.edu
References
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Alldredge A. L. & Cohen Y. 1987 Can microscale chemical patches persist in the sea? Microelectrode study of marine snow, fecal pellets. Science 235 (4789), 689691.
Alsinan A., Meiburg E. & Garaud P. 2017 A settling-driven instability in two-component, stably stratified fluids. J. Fluid Mech. 816, 243267.
Baines P. G. & Gill A. E. 1969 On thermohaline convection with linear gradients. J. Fluid Mech. 37, 289306.
Brown J. M., Garaud P. & Stellmach S. 2013 Chemical transport and spontaneous layer formation in fingering convection in astrophysics. Astrophys. J. 768, 34.
Burns P. & Meiburg E. 2012 Sediment-laden fresh water above salt water: linear stability analysis. J. Fluid Mech. 691, 279314.
Burns P. & Meiburg E. 2015 Sediment-laden fresh water above salt water: nonlinear simulations. J. Fluid Mech. 762, 156195.
Carazzo G. & Jellinek A. M. 2013 Particle sedimentation and diffusive convection in volcanic ash-clouds. J. Geophys. Res. 118 (4), 14201437.
Garaud P. 2013 Double-diffusive convection. In EAS Publications Series (ed. Alecian G., Lebreton Y., Richard O. & Vauclair G.), EAS Publications Series, vol. 63, pp. 285295.
Garaud P. & Brummell N. 2015 2D or Not 2D: the effect of dimensionality on the dynamics of fingering convection at low Prandtl number. Astrophys. J. 815, 42.
Green T. 1987 The importance of double diffusion to the settling of suspended material. Sedimentology 34 (2), 319331.
Ham J. M. & Homsy G. M. 1988 Hindered settling and hydrodynamic dispersion in quiescent sedimenting suspensions. Intl J. Multiphase Flow 14 (5), 533546.
Holyer J. Y. 1981 On the collective instability of salt fingers. J. Fluid Mech. 110, 195207.
Houk D. & Green T. 1973 Descent rates of suspension fingers. Deep Sea Res. 20, 757761.
Hoyal D. C. J. D., Bursik M. I. & Atkinson J. F. 1999a Settling-driven convection: a mechanism of sedimentation from stratified fluids. J. Geophys. Res. 104, 79537966.
Hoyal D. C. J. D., Bursik M. I. & Atkinson J. F. 1999b The influence of diffusive convection on sedimentation from buoyant plumes. Mar. Geol. 159 (14), 205220.
Krishnamurti R. 2003 Double-diffusive transport in laboratory thermohaline staircases. J. Fluid Mech. 483, 287314.
Krishnamurti R. 2009 Heat, salt and momentum transport in a laboratory thermohaline staircase. J. Fluid Mech. 638, 491506.
Kunze E. 2003 A review of oceanic salt-fingering theory. Prog. Oceanogr. 56 (3–4), 399417.
Lambert R. B. & Demenkow J. W. 1972 On the vertical transport due to fingers in double diffusive convection. J. Fluid Mech. 54, 627640.
Linden P. F. 1973 On the structure of salt fingers. Deep Sea Res. 20, 325340.
Maxworthy T. 1999 The dynamics of sedimenting surface gravity currents. J. Fluid Mech. 392, 2744.
Necker F., Härtel C., Kleiser L. & Meiburg E. 2002 High-resolution simulations of particle-driven gravity currents. Intl J. Multiphase Flow 28 (2), 279300.
Nicolai H., Herzhaft B., Hinch E. J., Oger L. & Guazzelli E. 1995 Particle velocity fluctuations and hydrodynamic self-diffusion of sedimenting non-brownian spheres. Phys. Fluids 7 (1), 1223.
Parsons J. D., Bush J. W. M. & Syvitski J. P. M. 2001 Hyperpycnal plume formation from riverine outflows with small sediment concentrations. Sedimentology 48, 465478.
Radko T. 2003 A mechanism for layer formation in a double-diffusive fluid. J. Fluid Mech. 497, 365380.
Radko T. 2013 Double-Diffusive Convection. Cambridge University Press.
Radko T. & Smith D. P. 2012 Equilibrium transport in double-diffusive convection. J. Fluid Mech. 692, 527.
Rosenblum E., Garaud P., Traxler A. & Stellmach S. 2011 Turbulent mixing and layer formation in double-diffusive convection: three-dimensional numerical simulations and theory. Astrophys. J. 731, 66.
Sánchez X. & Roget E. 2007 Microstructure measurements and heat flux calculations of a triple-diffusive process in a lake within the diffusive layer convection regime. J. Geophys. Res. 112 (C2), C02012.
Scheu K. R., Fong D. A., Monismith S. G. & Fringer O. B. 2015 Sediment transport dynamics near a river inflow in a large alpine lake. Limnol. Oceanogr. 60 (4), 11951211.
Schmitt R. W. 1979a The growth rate of super-critical salt fingers. Deep Sea Res. 26A, 2340.
Schmitt R. W. 1979b Flux measurements on salt fingers at an interface. J. Mar. Res. 37 (3), 419436.
Schmitt R. W. 1994 Double diffusion in oceanography. Annu. Rev. Fluid Mech. 26 (1), 255285.
Schmitt R. W. 1995 The salt finger experiments of Jevons (1857) and Rayleigh (1880). J. Phys. Oceanogr. 25 (1), 817.
Schmitt R. W. 2003 Observational and laboratory insights into salt finger convection. Prog. Oceanogr. 56, 419433.
Schmitt R. W., Ledwell J. R., Montgomery E. T., Polzin K. L. & Toole J. M. 2005 Enhanced diapycnal mixing by salt fingers in the thermocline of the tropical atlantic. Science 308 (5722), 685688.
Schmitt R. W., Perkins H., Boyd J. D. & Stalcup M. C. 1987 C-salt: an investigation of the thermohaline staircase in the western tropical north atlantic. Deep Sea Res. 34 (10), 16551665.
Segre P. N., Liu F., Umbanhowar P. & Weitz D. A. 2001 An effective gravitational temperature for sedimentation. Nature 409 (6820), 594597.
Stellmach S., Traxler A., Garaud P., Brummell N. & Radko T. 2011 Dynamics of fingering convection. Part 2. The formation of thermohaline staircases. J. Fluid Mech. 677, 554571.
Stern M. E. 1960 The salt fountain and thermohaline convection. Tellus 12 (2), 172175.
Stern M. E. 1969 Collective instability of salt fingers. J. Fluid Mech. 35, 209218.
Stern M. E., Radko T. & Simeonov J. 2001 Salt fingers in an unbounded thermocline. J. Mar. Res. 59 (3), 355390.
Stern M. E. & Simeonov J. A. 2002 Internal wave overturns produced by salt fingers. J. Phys. Oceanogr. 32, 36383656.
Stern M. E. & Turner J. S. 1969 Salt fingers and convecting layers. Deep Sea Res. 16 (1), 97511.
Tait R. I. & Howe M. R. 1968 Some observations of thermohaline stratification in the deep ocean. Deep Sea Res. 15, 275280.
Tait R. I. & Howe M. R. 1971 Thermohaline staircase. Nature 231 (5299), 178179.
Traxler A., Stellmach S., Garaud P., Radko T. & Brummell N. 2011 Dynamics of fingering convection. Part 1. Small-scale fluxes and large-scale instabilities. J. Fluid Mech. 677, 530553.
Turner J. S. 1967 Salt fingers across a density interface. Deep Sea Res. 14 (5), 599.
Turner J. S. 1974 Double-diffusive phenomena. Annu. Rev. Fluid Mech. 6 (1), 3754.
Turner J. S. 1985 Multicomponent convection. Annu. Rev. Fluid Mech. 17 (1), 1144.
Vauclair S. 2004 Metallic fingers and metallicity excess in exoplanets’ host stars: the accretion hypothesis revisited. Astrophys. J. 605 (2), 874879.
Yoshida J. & Nagashima H. 2003 Numerical experiments on salt-finger convection. Prog. Oceanogr. 56 (3), 435459.
You Y. 2002 A global ocean climatological atlas of the Turner angle: implications for double-diffusion and water-mass structure. Deep Sea Res. 49 (11), 20752093.
Yu X., Hsu T.-J. & Balachandar S. 2013 Convective instability in sedimentation: linear stability analysis. J. Geophys. Res. 118, 256272.
Yu X., Hsu T.-J. & Balachandar S. 2014 Convective instability in sedimentation: 3-D numerical study. J. Geophys. Res. 119, 81418161.
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Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
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