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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.

UKACM Proceedings 2024 (2024)
Presentation / Conference Contribution
(2024, April). UKACM Proceedings 2024. Presented at 2024 UK Association for Computational Mechanics Conference, Durham, UK

The proceedings present 52 scientific papers written for the 32nd conference of the UK Association for Computational Mechanics (UKACM). The papers submitted to UKACM 2024 cover the breadth of computational mechanics research within the UK and beyond... Read More about UKACM Proceedings 2024.

Mathematical modelling of pressure induced freezing point depression within soils exhibiting strong capillary pressure effect (2024)
Presentation / Conference Contribution
Lgotina, E., Mathias, S., Lloret-Cabot, M., & Ireson, A. (2024, April). Mathematical modelling of pressure induced freezing point depression within soils exhibiting strong capillary pressure effect. Presented at 2024 UK Association for Computational Mechanics Conference, Durham, UK

Many geotechnical applications are affected by the melting and formation of ice in soils. Current state of practice involves incorporating the presence of ice within hydrological models for unsaturated soils using the so-called generalised Clapeyron... Read More about Mathematical modelling of pressure induced freezing point depression within soils exhibiting strong capillary pressure effect.

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.

Hydraulics, Hydrology and Environmental Engineering (2023)
Book
Mathias, S. A. (2023). Hydraulics, Hydrology and Environmental Engineering. Springer. https://doi.org/10.1007/978-3-031-41973-7

This textbook provides an excellent resource for engineering and science students to develop basic, intermediate and advanced level skills in hydraulics, hydrology and environmental engineering. Topics include open channel flow, ocean waves, kinemati... Read More about Hydraulics, Hydrology and Environmental Engineering.

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.