Lei, Timan;
(2021)
Pore-scale study on porous media flows with chemical reaction using lattice Boltzmann method.
Doctoral thesis (Ph.D), University College London.
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Abstract
Porous media flows with chemical reaction are common in nature and widely exist in many scientific and industrial applications. However, due to the complexity of coupled mechanisms, numerical modelling and comprehensive understanding of such flows face significant challenges. Therefore, this thesis develops novel lattice Boltzmann (LB) models to undertake pore-scale simulations of porous media flows with chemical reaction. These models, with new reaction source terms and boundary schemes, can describe both homogeneous reaction between two fluids and heterogeneous reaction (dissolution or combustion) at the fluid-solid interface. Unlike previous studies, current models recast heat and mass transfer equations to correctly consider the thermal expansion effects and the conjugate heat transfer and species conservation conditions. Separate LB equations are also developed to include different species properties. Density fingering with homogeneous reaction is studied at the pore scale. By changing species contributions to density, diffusion coefficients, initial concentrations, and medium heterogeneities, results obtained demonstrate that reaction can enhance, suppress, or trigger fingering. Then, pore-scale simulations of viscous fingering with dissolution reaction are performed. Effects of fluid diffusion, chemical dissolution, and viscosity contrast are extensively assessed. Results illustrate four fingering regimes as stable, unstable, reactive stable, and reactive unstable. Finally, pore-scale coke combustion in porous media is studied. General combustion dynamics are correctly produced, verifying the superior performance of the present LB model over previous ones. A parametric study demonstrates that the inlet air temperature and the driving force are influential factors and should be constrained within certain ranges for stable combustion fronts. These pore-scale findings provide valuable insights, like temperature fluctuations at the fluid-solid interface, porous structure evolutions, exact reaction and diffusion rates, and medium heterogeneity effects, which are more precise and explicit than macroscopic results. Furthermore, detailed fingering and combustion dynamics under diverse conditions are helpful in scientific and industrial fields.
Type: | Thesis (Doctoral) |
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Qualification: | Ph.D |
Title: | Pore-scale study on porous media flows with chemical reaction using lattice Boltzmann method |
Event: | University College London |
Open access status: | An open access version is available from UCL Discovery |
Language: | English |
Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
URI: | https://discovery.ucl.ac.uk/id/eprint/10129852 |
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