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.
nonGeographicDataset
https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item182973
name: Data
function: download
https://doi.org/10.5285/a49db9b4-a44e-4a5d-9fd7-d5021bdfc770
name: Digital Object Identifier (DOI)
function: information
http://data.bgs.ac.uk/id/dataHolding/13608126
eng
geoscientificInformation
publication
2008-06-01
Comminution
NGDC Deposited Data
Lava flows
Pyroclastic rocks
revision
2022
NERC_DDC
2022-03-01
2022-08-01
creation
2023-11-06
notApplicable
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.
publication
2011
false
See the referenced specification
publication
2010-12-08
false
See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF
MS Excel
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University of Edinburgh
originator
University of South Florida
originator
University of Oregon
originator
University of South Florida
originator
British Geological Survey
distributor
British Geological Survey
pointOfContact
British Geological Survey
Environmental Science Centre,Keyworth
NOTTINGHAM
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United Kingdom
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pointOfContact
2024-04-18