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Professor Simon Mathias' Outputs (78)

Two Film Approach to Continuum Scale Mixing and Dispersion with Equilibrium Bimolecular Reaction (2024)
Journal Article
Mathias, S. A., Bolster, D., & Veremieiev, S. (2024). Two Film Approach to Continuum Scale Mixing and Dispersion with Equilibrium Bimolecular Reaction. Transport in Porous Media, 151(8), 1709-1727. https://doi.org/10.1007/s11242-024-02091-y

Reliable reactive transport models require careful separation of mixing and dispersion processes. Here we treat displacing and displaced fluids as two separate fluid phases and invoke Whitman’s classical two-film theory to model mass transfer between... Read More about Two Film Approach to Continuum Scale Mixing and Dispersion with Equilibrium Bimolecular Reaction.

Banding in the Margins of Basaltic Dykes Indicates Pulsatory Propagation During Emplacement (2024)
Journal Article
Allgood, C., Llewellin, E. W., Humphreys, M. C. S., Mathias, S. A., Brown, R. J., & Vye‐Brown, C. (2024). Banding in the Margins of Basaltic Dykes Indicates Pulsatory Propagation During Emplacement. Journal of Geophysical Research: Solid Earth, 129(4), Article e2023JB028007. https://doi.org/10.1029/2023jb028007

Basaltic fissure eruptions, which are the most common type of eruption on Earth, are fed by dykes which mediate magma transport through the crust. Dyke propagation processes are important because they determine the geometry of the transport pathway a... Read More about Banding in the Margins of Basaltic Dykes Indicates Pulsatory Propagation During Emplacement.

Revisiting Salvucci’s Semi-analytical Solution for Bare Soil Evaporation with New Consideration of Vapour Diffusion and Film Flow (2023)
Journal Article
Mathias, S. A., Sander, G. C., Leung, J., & Newall, S. R. (2023). Revisiting Salvucci’s Semi-analytical Solution for Bare Soil Evaporation with New Consideration of Vapour Diffusion and Film Flow. Transport in Porous Media, 147(2), 463-493. https://doi.org/10.1007/s11242-023-01917-5

Bare soil evaporation is controlled by a combination of capillary flow, vapour diffusion and film flow. Relevant analytical solutions mostly assume horizontal flow conditions and ignore gravitational effects. Salvucci (1997) provided a rare example o... Read More about Revisiting Salvucci’s Semi-analytical Solution for Bare Soil Evaporation with New Consideration of Vapour Diffusion and Film Flow.

A simple, efficient, mass-conservative approach to solving Richards' equation (openRE, v1.0) (2023)
Journal Article
Ireson, A. M., Spiteri, R. J., Clark, M. P., & Mathias, S. A. (2023). A simple, efficient, mass-conservative approach to solving Richards' equation (openRE, v1.0). Geoscientific Model Development, 16(2), 659-677. https://doi.org/10.5194/gmd-16-659-2023

A simple numerical solution procedure – namely the method of lines combined with an off-the-shelf ordinary differential equation (ODE) solver – was shown in previous work to provide efficient, mass-conservative solutions to the pressure-head form of... Read More about A simple, efficient, mass-conservative approach to solving Richards' equation (openRE, v1.0).

Numerical investigation on origin and evolution of polygonal cracks on rock surfaces (2022)
Journal Article
Chen, T., Foulger, G. R., Tang, C., Mathias, S. A., & Gong, B. (2022). Numerical investigation on origin and evolution of polygonal cracks on rock surfaces. Engineering Geology, 311, Article 106913. https://doi.org/10.1016/j.enggeo.2022.106913

We studied the formation and evolution mechanism of polygonal cracks on rock surfaces under cooling by modelling meso-damage mechanics, continuum mechanics and thermodynamics. Factors that affect rock surface damage include ambient temperature, litho... Read More about Numerical investigation on origin and evolution of polygonal cracks on rock surfaces.

Effect of H2S content on relative permeability and capillary pressure characteristics of acid gas/brine/rock systems: A review (2022)
Journal Article
Zhang, X., Li, Q., Mathias, S., Zheng, G., & Tan, Y. (2022). Effect of H2S content on relative permeability and capillary pressure characteristics of acid gas/brine/rock systems: A review. Journal of Rock Mechanics and Geotechnical Engineering, 14(6), 2003-2033. https://doi.org/10.1016/j.jrmge.2022.03.014

Geological storage of acid gas has been identified as a promising approach to reduce atmospheric carbon dioxide (CO2) and hydrogen sulfide (H2S) and alleviate public concern resulting from sour gas production. A good understanding of the relative per... Read More about Effect of H2S content on relative permeability and capillary pressure characteristics of acid gas/brine/rock systems: A review.

Strain characteristics and permeability evolution of faults under stress disturbance monitoring by fibre bragg grating sensing and pressure pulses (2021)
Journal Article
Xu, L., Li, Q., Mathias, S. A., Tan, Y., Yang, D., & Fan, C. (2021). Strain characteristics and permeability evolution of faults under stress disturbance monitoring by fibre bragg grating sensing and pressure pulses. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 7(4), Article 93. https://doi.org/10.1007/s40948-021-00289-8

The sealing and structural stability of faults must be considered in many underground engineering endeavours, such as underground energy extraction and CO2 geological storage. In order to simultaneously study the evolution laws of fault sealing and s... Read More about Strain characteristics and permeability evolution of faults under stress disturbance monitoring by fibre bragg grating sensing and pressure pulses.

A Model for the Soil Freezing Characteristic Curve That Represents the Dominant Role of Salt Exclusion (2021)
Journal Article
Amankwah, S., Ireson, A., Maulé, C., Brannen, R., & Mathias, S. (2021). A Model for the Soil Freezing Characteristic Curve That Represents the Dominant Role of Salt Exclusion. Water Resources Research, 57(8), Article e2021WR030070. https://doi.org/10.1029/2021wr030070

The phenomenon of freezing point depression in frozen soils results in the co-existence of ice and liquid water in soil pores at temperatures below 273.15 K (0°C), and is thought to have two causes: (a) capillary and adsorption effects, where the pha... Read More about A Model for the Soil Freezing Characteristic Curve That Represents the Dominant Role of Salt Exclusion.

Pseudospectral methods provide fast and accurate solutions for the horizontal infiltration equation (2021)
Journal Article
Mathias, S. A., & Sander, G. C. (2021). Pseudospectral methods provide fast and accurate solutions for the horizontal infiltration equation. Journal of Hydrology, 598, Article 126407. https://doi.org/10.1016/j.jhydrol.2021.126407

An extremely fast and accurate pseudospectral numerical method is presented, which can be used in inverse methods for estimating soil hydraulic parameters from horizontal infiltration or desorption experiments. Chebyshev polynomial dierentiation in c... Read More about Pseudospectral methods provide fast and accurate solutions for the horizontal infiltration equation.

Transmission loss estimation for ephemeral sand rivers in Southern Africa (2021)
Journal Article
Mathias, S. A., Reaney, S. M., & Kenabatho, P. K. (2021). Transmission loss estimation for ephemeral sand rivers in Southern Africa. Journal of Hydrology, 600, Article 126487. https://doi.org/10.1016/j.jhydrol.2021.126487

Ephemeral sand rivers represent an important water resource in Southern Africa. These rivers only flow for a few days in a year. However, much of this water infiltrates the underlying river bed sediments where it is protected from evaporation and uti... Read More about Transmission loss estimation for ephemeral sand rivers in Southern Africa.

An experimentally validated numerical model for bubble growth in magma (2020)
Journal Article
Coumans, J., Llewellin, E., Wadsworth, F., Humphreys, M., Mathias, S., Yelverton, B., & Gardner, J. (2020). An experimentally validated numerical model for bubble growth in magma. Journal of Volcanology and Geothermal Research, 402, Article 107002. https://doi.org/10.1016/j.jvolgeores.2020.107002

Volcanic eruptions are driven by the growth of gas bubbles in magma. The timing and rate of bubble growth are important because they determine whether enough gas pressure can develop to fragment the melt. Bubbles grow in response to decompression and... Read More about An experimentally validated numerical model for bubble growth in magma.

An experimentally-validated numerical model of diffusion and speciation of water in rhyolitic silicate melt (2020)
Journal Article
Coumans, J. P., Llewellin, E. W., Humphreys, M. C., Nowak, M., Brooker, R. A., Mathias, S. A., & McIntosh, I. M. (2020). An experimentally-validated numerical model of diffusion and speciation of water in rhyolitic silicate melt. Geochimica et Cosmochimica Acta, 276, 219-238. https://doi.org/10.1016/j.gca.2020.02.026

The diffusion of water through silicate melts is a key process in volcanic systems. Diffusion controls the growth of the bubbles that drive volcanic eruptions and determines the evolution of the spatial distribution of dissolved water during and afte... Read More about An experimentally-validated numerical model of diffusion and speciation of water in rhyolitic silicate melt.

Gas diffusion in coal powders is a multi-rate process (2019)
Journal Article
Mathias, S., Dentz, M., & Liu, Q. (2020). Gas diffusion in coal powders is a multi-rate process. Transport in Porous Media, 131, 1037-1051. https://doi.org/10.1007/s11242-019-01376-x

Gas migration in coal is strongly controlled by surface diffusion of adsorbed gas within the coal matrix. Surface diffusion coefficients are obtained by inverse modelling of transient gas desorption data from powdered coals. The diffusion coefficient... Read More about Gas diffusion in coal powders is a multi-rate process.

Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions (2019)
Journal Article
Mathias, S. A., Nielsen, S., & Ward, R. L. (2019). Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions. Transport in Porous Media, 130(2), 627-636. https://doi.org/10.1007/s11242-019-01331-w

The porosity and permeability of coal change with pore pressure, due to changes in effective stress and matrix swelling due to gas adsorption. Three analytical models to describe porosity and permeability change in this context have been presented in... Read More about Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions.

Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer (2019)
Journal Article
Jayeoba, A., Mathias, S. A., Nielsen, S., Vilarrasa, V., & Bjørnarå, T. I. (2019). Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer. Journal of Hydrology, 573, 964-969. https://doi.org/10.1016/j.jhydrol.2019.03.041

Ground surface subsidence due to groundwater production is a significant problem. Many attempts have been made to develop analytical models to forecast subsidence rates as a consequence of groundwater production. Previous analytical solutions either... Read More about Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer.

Capillary processes increase salt precipitation during CO2 injection in saline formations (2018)
Journal Article
Kelly, H. L., & Mathias, S. A. (2018). Capillary processes increase salt precipitation during CO2 injection in saline formations. Journal of Fluid Mechanics, 852, 398-421. https://doi.org/10.1017/jfm.2018.540

An important attraction of saline formations for CO2 storage is that their high salinity renders their associated brine unlikely to be identified as a potential water resource in the future. However, high salinity can lead to dissolved salt precipita... Read More about Capillary processes increase salt precipitation during CO2 injection in saline formations.

Masuda's sandstone core hydrate dissociation experiment revisited (2017)
Journal Article
Hardwick, J., & Mathias, S. (2018). Masuda's sandstone core hydrate dissociation experiment revisited. Chemical Engineering Science, 175, 98-109. https://doi.org/10.1016/j.ces.2017.09.003

Numerical simulation of hydrate dissociation in porous media is important to investigate future hydrate fuel extraction strategies and/or the impacts of climate change on the long-term stability of vulnerable near-surface hydrate deposits. The core-s... Read More about Masuda's sandstone core hydrate dissociation experiment revisited.

Gas venting that bypasses the feather edge of marine hydrate, offshore Mauritania (2017)
Journal Article
Li, A., Davies, R. J., Mathias, S., Yang, J., Hobbs, R., & Wilson, M. (2017). Gas venting that bypasses the feather edge of marine hydrate, offshore Mauritania. Marine and Petroleum Geology, 88, 402-409. https://doi.org/10.1016/j.marpetgeo.2017.08.026

Methane can be released from the vast marine hydrate reservoirs that surround continents into oceans and perhaps the atmosphere. But how these pathways work within the global carbon cycle now and during a warmer world is only partially understood. He... Read More about Gas venting that bypasses the feather edge of marine hydrate, offshore Mauritania.

Analytical solution for clay plug swelling experiments (2017)
Journal Article
Mathias, S., Greenwell, H., Withers, C., Erdogan, A., McElwaine, J., & MacMinn, C. (2017). Analytical solution for clay plug swelling experiments. Applied Clay Science, 149, 75-78. https://doi.org/10.1016/j.clay.2017.07.021

Clay swelling experiments frequently involve monitoring the one-dimensional displacement with time of an initially dry clay plug as it imbibes water from a supply at its base. This article presents a new analytical solution for interpreting such expe... Read More about Analytical solution for clay plug swelling experiments.