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Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents

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Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents. / Smith, Gregory M.; Williams, Rebecca; Rowley, Pete J.; Parsons, Daniel R.

In: Bulletin of Volcanology, Vol. 80, No. 8, 67, 01.08.2018.

Research output: Contribution to journalArticlepeer-review

Harvard

Smith, GM, Williams, R, Rowley, PJ & Parsons, DR 2018, 'Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents', Bulletin of Volcanology, vol. 80, no. 8, 67. https://doi.org/10.1007/s00445-018-1241-1

APA

Smith, G. M., Williams, R., Rowley, P. J., & Parsons, D. R. (2018). Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents. Bulletin of Volcanology, 80(8), [67]. https://doi.org/10.1007/s00445-018-1241-1

Vancouver

Author

Smith, Gregory M. ; Williams, Rebecca ; Rowley, Pete J. ; Parsons, Daniel R. / Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents. In: Bulletin of Volcanology. 2018 ; Vol. 80, No. 8.

Bibtex

@article{ec24cbd7d8b44d9984ad4fb85c89de6e,
title = "Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents",
abstract = "The high mobility of dense pyroclastic density currents (PDCs) is commonly attributed to high gas pore pressures. However, the influence of spatial and temporal variations in pore pressure within PDCs has yet to be investigated. Theory suggests that variability in the fluidisation and aeration of a current will have a significant control on PDC flow and deposition. In this study, the effect of spatially heterogeneous gas pore pressures in experimental PDCs was investigated. Sustained, unsteady granular currents were released into a flume channel where the injection of gas through the channel base was controlled to create spatial variations in aeration. Maximum current front velocity results from high degrees of aeration proximal to the source, rather than lower sustained aeration along the whole flume channel. However, moderate aeration (i.e. ~ 0.5 minimum static fluidisation velocity (Umf_st)) sustained throughout the propagation length of a current results in greater runout distances than currents which are closer to fluidisation (i.e. 0.9 Umf_st) near to source, then de-aerating distally. Additionally, although all aerated currents are sensitive to channel base slope angle, the runout distance of those currents where aeration is sustained throughout their lengths increases by up to 54% with an increase of slope from 2° to 4°. Deposit morphologies a primarily controlled by the spatial differences in aeration, where there is a large decrease in aeration the current forms a thick depositional wedge. Sustained gas-aerated granular currents are observed to be spontaneously unsteady, with internal sediment waves travelling at different velocities.",
author = "Smith, {Gregory M.} and Rebecca Williams and Rowley, {Pete J.} and Parsons, {Daniel R.}",
year = "2018",
month = aug,
day = "1",
doi = "10.1007/s00445-018-1241-1",
language = "English",
volume = "80",
journal = "Bulletin of Volcanology",
issn = "0258-8900",
publisher = "Springer Verlag",
number = "8",

}

RIS

TY - JOUR

T1 - Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents

AU - Smith, Gregory M.

AU - Williams, Rebecca

AU - Rowley, Pete J.

AU - Parsons, Daniel R.

PY - 2018/8/1

Y1 - 2018/8/1

N2 - The high mobility of dense pyroclastic density currents (PDCs) is commonly attributed to high gas pore pressures. However, the influence of spatial and temporal variations in pore pressure within PDCs has yet to be investigated. Theory suggests that variability in the fluidisation and aeration of a current will have a significant control on PDC flow and deposition. In this study, the effect of spatially heterogeneous gas pore pressures in experimental PDCs was investigated. Sustained, unsteady granular currents were released into a flume channel where the injection of gas through the channel base was controlled to create spatial variations in aeration. Maximum current front velocity results from high degrees of aeration proximal to the source, rather than lower sustained aeration along the whole flume channel. However, moderate aeration (i.e. ~ 0.5 minimum static fluidisation velocity (Umf_st)) sustained throughout the propagation length of a current results in greater runout distances than currents which are closer to fluidisation (i.e. 0.9 Umf_st) near to source, then de-aerating distally. Additionally, although all aerated currents are sensitive to channel base slope angle, the runout distance of those currents where aeration is sustained throughout their lengths increases by up to 54% with an increase of slope from 2° to 4°. Deposit morphologies a primarily controlled by the spatial differences in aeration, where there is a large decrease in aeration the current forms a thick depositional wedge. Sustained gas-aerated granular currents are observed to be spontaneously unsteady, with internal sediment waves travelling at different velocities.

AB - The high mobility of dense pyroclastic density currents (PDCs) is commonly attributed to high gas pore pressures. However, the influence of spatial and temporal variations in pore pressure within PDCs has yet to be investigated. Theory suggests that variability in the fluidisation and aeration of a current will have a significant control on PDC flow and deposition. In this study, the effect of spatially heterogeneous gas pore pressures in experimental PDCs was investigated. Sustained, unsteady granular currents were released into a flume channel where the injection of gas through the channel base was controlled to create spatial variations in aeration. Maximum current front velocity results from high degrees of aeration proximal to the source, rather than lower sustained aeration along the whole flume channel. However, moderate aeration (i.e. ~ 0.5 minimum static fluidisation velocity (Umf_st)) sustained throughout the propagation length of a current results in greater runout distances than currents which are closer to fluidisation (i.e. 0.9 Umf_st) near to source, then de-aerating distally. Additionally, although all aerated currents are sensitive to channel base slope angle, the runout distance of those currents where aeration is sustained throughout their lengths increases by up to 54% with an increase of slope from 2° to 4°. Deposit morphologies a primarily controlled by the spatial differences in aeration, where there is a large decrease in aeration the current forms a thick depositional wedge. Sustained gas-aerated granular currents are observed to be spontaneously unsteady, with internal sediment waves travelling at different velocities.

U2 - 10.1007/s00445-018-1241-1

DO - 10.1007/s00445-018-1241-1

M3 - Article

VL - 80

JO - Bulletin of Volcanology

JF - Bulletin of Volcanology

SN - 0258-8900

IS - 8

M1 - 67

ER -

ID: 11237121