Fluid dynamics
Type of resources
Topics
Keywords
Contact for the resource
Provided by
Years
Formats
Update frequencies

Shallow overland flows in steady state can become unstable and break up into destructive surges. The following data documents maximum growth rates for disturbances to uniform steady flows on a fixed slope in a onedimensional shallowlayer model that incorporates the mechanics of erosion and deposition of monodisperse sediment, documented in sections 2 and 4 of the following freely available preprint: https://arxiv.org/abs/2007.15989. The data comprises the following 4 columns, separated by spaces: grain diameter, Froude number, solid fraction and maximum growth rate. Grain diameter refers to the characteristic diameter of erodible particles, nondimensionalised by the steady flow depth h0. Froude number, Fr, is a dimensionless constant defined as Fr = u0 / sqrt(h0 * g'), where u0 is the velocity of the steady flow and g' is gravitational acceleration resolved perpendicular to the slope. Solid fraction is a number between 0 and 1 that describes the proportion of solid particles in the flowing mixture. A solid fraction of 0 denotes a purely fluid flow and a solid fraction of 1 denotes a saturated mixture containing a maximum packing of solid particles. Maximum growth rate refers to the largest linear growth rate for perturbations to a uniform flowing layer with the corresponding properties given in the prior 3 columns. The model formulation describes the dynamics of 4 unknown observables: flow height, flow velocity, solids concentration and bed height. By taking the 'maximum' in this case, we mean the maximum over these 4 flow fields that may be perturbed by an environmental disturbance and also the maximum over all possible wavelengths of disturbance. We note that in this dataset, flows with a maximum growth rate equal to zero or small positive values (e.g. up to machine precision) are stable; flows with strictly positive growth rate are unstable. Zero growth rate indicates that the maximum growth rate is given by a neutrally stable perturbation and such perturbations always exist for reasons of symmetry in the model. For each grain diameter and Froude number in the dataset, there exist two steady uniform states with different solid fractions. Therefore two files are supplied  one containing data for the more dilute states and the other containing data for the more concentrated states. These various technical details, as well as full documentation of the model and the parameters used are explained more fully in the aforementioned paper.

These data consist of spatial and temporal datasets for 11 different smallscale laboratory experiments of fluiddriven fractures, described in the paper Up, down, and round again: the circulating flow dynamics of fluxdriven fractures (Chalk and Kavanagh, accepted in Physics of Fluids, February 2024). These experiments, conducted at the University of Liverpool, are analogue models of natural fluiddriven fractures in glacial and magmatic settings. Fractures were created by injecting water or silicone oil into transparent gelatine at a constant rate. The total experimental data set consists of 11 different experiments named: S1,S2,S3,S4,S5,W1,W2,W3,W4,SH,WH. S experiments involve the injection of silicone oil, and W experiments involve the injection of water. The raw data consist of a temporal series of jpegs from camera recordings of each experiment, located in the subdirectory "frames". For all experiments except for WH and SH, the data also consist of a temporal series of csv files containing spatial velocity data of the internal fluid flow, located in the subdirectory "PIV". These data are described in further detail in the metadata file in the raw data directory.

Results files from computer simulations of fluid flow for 3D models of Ediacaran organisms and communities, generated using computational fluid dynamics. Simulations performed using the simulation software package COMSOL Multiphysics. Root folder names refer to initial trials ‘Cylinder Tests’), modern organisms (‘Chondrocladia lyra’), Ediacaran organisms (‘Pectinifrons’ and ‘Pterdinium’), and Ediacaran surfaces (‘Avalon’ and ‘White Sea’ surfaces). Subfolder and file names refer to simulations performed with different models (e.g., ‘Base’, ‘Filled’ and ‘Flush’ Petridinium models), model orientations (e.g., 0°, 90°, and 180° to the inlet), current velocities (e.g., 0.15, 0.5 and 0.85 m/s), and turbulence models (e.g., Spalart Allmaras, shear stress transport, and large eddy simulation). Further details for Pectinifrons and Pteridinium available in Darroch et al. 2022 (https://doi.org/10.1017/pab.2022.2) and Darroch et al. 2023 (https://doi.org/10.1016/j.isci.2023.105989), respectively. Files can be opened with COMSOL Multiphysics (www.comsol.com) versions 5.6 or 6.0 and above.