NDLI: Volcanic jets, plumes, and collapsing fountains: evidence from large-scale experiments, with particular emphasis on the entrainment rate

Content Provider	Springer Nature Link
Author	Delli, P. Dioguardi, F. Mele, D. D’Addabbo, M. Zimawski, B. Büttner, R. Doronzo, D. M. Sonder, I. Sulpizio, R. Dürig, T. Volpe, L.
Copyright Year	2014
Abstract	The source conditions of volcanic plumes and collapsing fountains are investigated by means of large-scale experiments. In the experiments, gas-particle jets issuing from a cylindrical conduit are forced into the atmosphere at different mass flow rates. Dense jets (high particle volumetric concentration, e.g., C 0 > 0.01) generate collapsing fountains, whose height scales with the squared exit velocity. This is consistent with Bernoulli’s equation, which is a good approximation if air entrainment is negligible. In this case, kinetic energy is transformed into potential energy without any significant loss by friction with the atmosphere. The dense collapsing fountain, on hitting the ground, generates an intense shear flow similar to a pyroclastic density current. Dilute hot jets (low particle volumetric concentration, e.g., C 0 < 0.01) dissipate their initial kinetic energy at much smaller heights than those predicted by Bernoulli’s equation. This is an indication that part of the total mechanical energy is lost by friction with the atmosphere. Significant air entrainment results in this case, leading to the formation of a buoyant column (plume) from which particles settle similarly to pyroclastic fallout. The direct measurement of entrainment coefficient in the experiments suggests that dense collapsing fountains form only when air entrainment is not significant. This is a consequence of the large density difference between the jet and the atmosphere. Cold dilute experiments result in an entrainment coefficient of about 0.06, which is typical of pure jets of fluid dynamics. Hot dilute experiments result in an entrainment coefficient of about 0.11, which is typical of thermally buoyant plumes. The entrainment coefficients obtained by experiments were used as input data in numerical simulations of fountains and plumes. A numerical model was used to solve the classic top-hat system of governing equations, which averages the field variables (e.g., column velocity and density) across the column. The maximum heights calculated with the model agree well with those observed experimentally, showing that our entrainment coefficients are compatible with a top-hat model. Dimensional analysis of the experimental data shows that a value of 3 for the source densimetric Froude number characterizes the transition between dense collapsing fountains and dilute plumes. This value delimits the source conditions (exit velocity, conduit radius, and particle volumetric concentration) for pyroclastic flow (<3) and fallout (>3).
Starting Page	1
Ending Page	18
Page Count	18
File Format	PDF
ISSN	02588900
Journal	Bulletin of Volcanology
Volume Number	76
Issue Number	6
e-ISSN	14320819
Language	English
Publisher	Springer Berlin Heidelberg
Publisher Date	2014-06-01
Publisher Place	Berlin/Heidelberg
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Explosive eruptions Eruptive columns Negatively buoyant jets Collapsing fountains Densimetric Froude number Turbulent entrainment Geology Geophysics/Geodesy Mineralogy Sedimentology
Content Type	Text
Resource Type	Article
Subject	Geochemistry and Petrology

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Plume height, volume, and classification of explosive volcanic eruptions based on the Weibull function

Uncertainty analysis of a model of wind-blown volcanic plumes

The frequency of explosive volcanic eruptions in Southeast Asia

Particle recycling in volcanic plumes

Andesitic Plinian eruptions at Mt. Ruapehu: quantifying the uppermost limits of eruptive parameters

Sulfur as a binding agent of aggregates in explosive eruptions

Sensitivity of the dynamics of volcanic eruption columns to their shape

Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania : II. Eruptive behaviour during the 2007–2008 explosive eruptions

Reconstructing the largest explosive eruptions of Mt. Ruapehu, New Zealand: lithostratigraphic tools to understand subplinian–plinian eruptions at andesitic volcanoes

Volcanic jets, plumes, and collapsing fountains: evidence from large-scale experiments, with particular emphasis on the entrainment rate

Similar Documents

Plume height, volume, and classification of explosive volcanic eruptions based on the Weibull function

Uncertainty analysis of a model of wind-blown volcanic plumes

The frequency of explosive volcanic eruptions in Southeast Asia

Particle recycling in volcanic plumes

Andesitic Plinian eruptions at Mt. Ruapehu: quantifying the uppermost limits of eruptive parameters

Sulfur as a binding agent of aggregates in explosive eruptions

Sensitivity of the dynamics of volcanic eruption columns to their shape

Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania : II. Eruptive behaviour during the 2007–2008 explosive eruptions

Reconstructing the largest explosive eruptions of Mt. Ruapehu, New Zealand: lithostratigraphic tools to understand subplinian–plinian eruptions at andesitic volcanoes

Volcanic jets, plumes, and collapsing fountains: evidence from large-scale experiments, with particular emphasis on the entrainment rate