Letter | Published:

Entrainment in turbulent gravity currents

Nature volume 362, pages 829831 (29 April 1993) | Download Citation

Subjects

Abstract

LABORATORY gravity currents are frequently used to model a range of environmental and industrial flows1. The manner in which these flows become diluted with distance by the surrounding fluid has important implications for turbidity currents2, pyroclastic flows3,4, avalanches5, accidental dense gas releases6, fire propagation7 and emission of industrial pollutants. Here we present an experimental technique for quantifying the entrainment of ambient fluid into the head of a gravity current propagating along a horizontal surface. The technique relies on the neutralization of an alkaline current by entrainment of acidic ambient fluid, and is visualized by using a pH indicator. Dimensional analysis indicates that the proportion of ambient fluid entrained into a gravity current head depends only on the initial volume of the current and distance from the release point, and is independent of the initial value of the density difference. This result is confirmed by the experimental data, which also show that little dilution of the head takes place during the slumping phase8,9. Thereafter the dilution increases with the downstream distance, in quantitative agreement with the predictions of a theoretical model which evaluates the volume of entrained fluid. We apply the results to show that sediment slumps of initially high sediment concentrations will become dilute turbidity currents owing to entrainment of sea water before they have propagated extensively over the floors of ocean basins.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    Gravity Currents in the Environment and the Laboratory (Halsted, Chichester, 1987).

  2. 2.

    Principles of Physical Sedimentology (Allen & Unwin, London, 1985).

  3. 3.

    Sci. prog. Oxf. 70, 171–207 (1986).

  4. 4.

    et al. Earth planet. Sci. Lett. 114, 243–257 (1993).

  5. 5.

    A. Rev. Fluid Mech. 15, 47–76 (1983).

  6. 6.

    A. Rev. Fluid Mech. 21, 317–344 (1989).

  7. 7.

    Proc. 3rd int. Symp. Fire Safety Science (eds Cox, G. & Langford, B.) 249–260 (Elsevier, London, 1991).

  8. 8.

    & J. Fluid Mech. 99, 785–799 (1980).

  9. 9.

    & J. Fluid Mech. 135, 95–110 (1983).

  10. 10.

    A. Rev. Fluid Mech. 4, 341–368 (1972).

  11. 11.

    J. Fluid Mech 121, 43–58 (1982).

  12. 12.

    , , , & Geology 13, 538–541 (1985).

  13. 13.

    & Am. J. Sci. 250, 849–873 (1952).

  14. 14.

    , & Deep-Sea Res. 1, 193–202 (1954).

Download references

Author information

Affiliations

  1. Institute of Theoretical Geophysics, Departments of Earth Sciences and Applied Mathematics and Theoretical Physics, University of Cambridge, 20 Silver Street, Cambridge CBS 9EW, UK

    • Mark A. Hallworth
    •  & Herbert E. Huppert
  2. Department of Geology, University of Bristol, Bristol BS8 1RJ, UK

    • Jeremy C. Phillips
    •  & R. Stephen J. Sparks

Authors

  1. Search for Mark A. Hallworth in:

  2. Search for Jeremy C. Phillips in:

  3. Search for Herbert E. Huppert in:

  4. Search for R. Stephen J. Sparks in:

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/362829a0

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.