MFIX simulation input files and results of simulation of fragmentation-induced fluidization, and laboratory analyses of volcanic pyroclastic density current material (NERC Grant NE/V014242/1)

MFIX (Multiphase Flow with Interphase eXchanges) simulation input files and results of simulation of fragmentation-induced fluidization, and laboratory analyses of volcanic pyroclastic density current material. The data consists of: 1) the Fortran90 input files for the MFIX (Multiphase Flow with Interphase eXchanges) TFM simulation runs, 2) the postprocessed MFIX results from our simulations present within Excel sheets 3) laboratory results on the particle shape, size distribution and porosity of the volcanic granular mixtures, presented within Excel sheets. The dataset presented was gathered to investigate the role of compaction, resulting from particle fragmentation, within volcanic granular flows known as pyroclastic density currents. The presented results were obtained from a combination of laboratory analyses and numerical modelling, using Computational Fluid Dynamics. In the laboratory, characterization of the particle size distributions and shape of volcanic grains was undertaken to understand their packing properties. Using the Two-Fluid Model (TFM), an Eulerian-Eulerian method, I was able to simulate the effect of particle breakage on natural scale volcanic mixtures. This model supports a broad range of capabilities for dense multiphase flow. The code was used to investigate the role of particle breakage in pyroclastic density currents, which alters the maximum packing of the granular mixture and ultimately the concentration of the flow during transport. Because the solid phase is immersed in air, the code allowed me to simulate the self-fluidization of the volcanic mixture and the effect on its flowability. These simulations enable me to propose a new process that can play a large role in the occurrence of long runout deadly pyroclastic density currents: Fragmentation-Induced Fluidization. The laboratory work was conducted at the University of Oregon (USA) while the numerical work was completed by running the simulations on the UKRI ARCHER2 HPC and the Talapas Cluster from the University of Oregon (US). The data processing was ongoing from August 2021 to December 2021 (Lab analyses) and February 2022 to August 2022 (HPC work). The MFIX simulation results have been post-processed using ParaView open-source software but can be reproduced by the user using the MFIX custom-changed subroutines and input files contained within the dataset. The data was collected to test the hypothesis that compaction, and subsequent self-fluidization is key to the long-runout of pyroclastic density currents. Specialized audience that work on granular media and volcanic flows. The MFIX code that is modified from the core code from the Department of Energy (DOE) is all present. The missing core code can be downloaded from the DOE department https://mfix.netl.doe.gov/. All the experimental data from lab experiments are presented.

Date (Creation): 2023-11-06

Citation identifier: http://data.bgs.ac.uk/id/dataHolding/13608126

Point of contact

Organisation name	Individual name	Electronic mail address	Role
University of Edinburgh	Eric Breard	not available	Originator
University of South Florida	Sylvain Charbonnier	not available	Originator
University of Oregon	Josef Dufek	not available	Originator
University of South Florida	Valentin Gueugneau	not available	Originator
British Geological Survey	Enquiries	not available	Distributor
British Geological Survey	Enquiries	not available	Point of contact

Maintenance and update frequency: notApplicable

GEMET - INSPIRE themes, version 1.0

Geology

BGS Thesaurus of Geosciences

Comminution
NGDC Deposited Data
Lava flows
Pyroclastic rocks

dataCentre

NGDC Deposited Data

Keywords

NERC_DDC

Access constraints: Other restrictions

Other constraints: licenceOGL

Other constraints: Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Use constraints: Other restrictions

Other constraints: The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.

Other constraints: Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Language: English

Topic category

Geoscientific information

Begin date: 2022-03-01

End date: 2022-08-01

Reference System Information

No information provided.

Distribution format

Name	Version
MS Excel
Text files

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
British Geological Survey	Enquiries	not available	Distributor

OnLine resource

Protocol	Linkage	Name
	https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item182973	Data

OnLine resource

Protocol	Linkage	Name
	https://doi.org/10.5285/a49db9b4-a44e-4a5d-9fd7-d5021bdfc770	Digital Object Identifier (DOI)

Hierarchy level: Non geographic dataset

Other: non geographic dataset

Conformance result

Title: INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology

Date (Publication): 2011

Explanation: See the referenced specification

Pass: No

Conformance result

Title: Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services

Date (Publication): 2010-12-08

Explanation: See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF

Pass: No

Statement: We analyzed pyroclastic density current samples by sieving and measured clast density for each size fraction and calculating the samples porosity (also called voidage) using a pycnometer. This approach is valid for various grain sizes, assuming limited pore connectivity in particles. For the Merapi BAF samples from 2006 and 2010, particle size and shape were studied using a dynamic image analyzer at the University of Oregon, analyzing 3000 particles per size bin for accuracy. In the lab, we also examined the random-close packing of granular samples. This involved measuring the mixture's bulk density and comparing it to the average particle density from pycnometer analysis. The method, validated with glass beads and then applied to volcanic particles, yielded consistent results over 10 experiments. To achieve a uniform grain-size distribution in the samples, we layered the mixture in the cylinder, ensuring each layer was four times the diameter of the largest particles. We used the Eulerian-Eulerian approach, known as the Two-Fluid Model (TFM), to study the impact of particle fragmentation on compaction in pyroclastic flows. Our 2D simulations were conducted using the MFIX code from the US Department of Energy's NETL. These simulations focused on mass and momentum equations for fluid and solid phases, excluding energy equations due to negligible cooling in dense granular mixtures, as evidenced by block-and-ash flow temperature measurements. The simulated multiphase mixture comprised air at 773 Kelvin and two solid particle sizes: 0.01 m and 100 microns, the latter representing fragmented particles. We set the friction coefficients at 0.7 and 0.6 for the mixture and basal layer, respectively, and used established theories for calculating kinetic and frictional stresses. Our simulation setup involved a 2D vertical column, representing a volcanic slope, to study the dynamics of fragmenting granular columns. We adjusted the gravity vector to mimic slope effects, monitoring the mixture's movement and defluidization along the slope. Fragmentation rates and a range of flow heights were tested to reflect natural conditions accurately. The chosen particle sizes ensured proper representation of natural block-and-ash flows. Sensitivity analysis validated the robustness of our results, with additional flow height and ash-generation rate estimates based on previous studies and field observations. The MFIX simulation results have been post-processed using ParaView open-source software but can be reproduced by the user using the MFIX custom-changed subroutines and input files contained within the dataset.