Abstract:A novel pore network model algorithm is developed to probe the effect of grain shape on multiphase displacement in porous media.• Systematic simulations are conducted using the proposed algorithm across a wide range of wetting conditions and particle shapes.• Through analyzing various metrics during displacement, the results highlight the profound influence of particle shape on multiphase flow.
“…A pore-resolved interface tracking algorithm is used for simulating multiphase flow processes in the capillary-dominated regime (Wang et al. 2021, 2022). The capillary-dominated regime (in the limit of vanishing capillary number), or the quasi-static regime, corresponds to displacement processes where the viscous effect (regardless of viscosity ratio) is negligible compared with the interfacial tension.…”
Section: Methodsmentioning
confidence: 99%
“…A detailed description of the algorithm can be found in the previous study (Wang et al. 2021, 2022) and is omitted here for brevity. Figure 1.Fluid displacement in regular porous media composed of circles packed on a triangular lattice.…”
Section: Methodsmentioning
confidence: 99%
“…2021; Wang et al. 2021). Interestingly, when the porosity of porous medium decreases below a critical value, the emergence of unstable invasion associated with rough invasion fronts and occurrence of trapping events is observed, which is reminiscent of invasion percolation (or capillary fingering in drainage condition).…”
Section: Introductionmentioning
confidence: 99%
“…In regular porous media – e.g. two-dimensional micromodels composed of circular posts with narrow particle size distribution arranged on a triangular or square lattice – both simulations and experiments have shown compact and faceted patterns (Cieplak & Robbins 1990; Martys, Robbins & Cieplak 1991; Holtzman 2016; Wang, Pereira & Gan 2021). This phenomenon was attributed to the dominance of the underlying pore geometry (regular lattice structure), which results in the symmetrical growth of invasion patterns.…”
Section: Introductionmentioning
confidence: 99%
“…However, when heterogeneity is introduced to particle shape (Wang et al. 2021), size (Lenormand 1990; Holtzman 2016; Hu et al. 2019) or position (Wang et al.…”
The unstable fluid–fluid displacement patterns in porous media with rough invasion fronts and trapping of the defending phase are often observed in drainage, i.e. when the solid is non-wetting to the invading phase. On the other hand, during imbibition, compact and faceted growth is expected in regular porous media with geometrically homogeneous pore structure. Here, we report the irregular growth of invading fluid during the imbibition process in two-dimensional regular porous media. The ramified invasion morphology associated with thin fingers is reminiscent of capillary fingering. Through examining the capillary pressure signals and the type of pore-scale invasion mechanisms, the fundamental differences between faceted growth and irregular invasion are revealed. By analysing the pore-scale invasion mechanisms, a phase diagram describing the dominance of different invasion events is proposed. Through conducting systematic quasi-static radial injection simulations across a wide range of porosity and wettability, excellent agreement is observed on the transition boundary from faceted and compact displacement patterns to irregular and dendritic invasion morphologies. This is reflected by the overlap of the transition boundaries from analytical prediction, type of pore-scale invasion events, and macroscopic morphology quantified by the fractal dimension. This work provides new insights on the role of geometrical features of solid structures during multiphase flow with emphasis on the porosity and wettability. The findings could assist in guiding the design of microfluidic devices to control deterministically the multiphase flow, transport and reaction processes.
“…A pore-resolved interface tracking algorithm is used for simulating multiphase flow processes in the capillary-dominated regime (Wang et al. 2021, 2022). The capillary-dominated regime (in the limit of vanishing capillary number), or the quasi-static regime, corresponds to displacement processes where the viscous effect (regardless of viscosity ratio) is negligible compared with the interfacial tension.…”
Section: Methodsmentioning
confidence: 99%
“…A detailed description of the algorithm can be found in the previous study (Wang et al. 2021, 2022) and is omitted here for brevity. Figure 1.Fluid displacement in regular porous media composed of circles packed on a triangular lattice.…”
Section: Methodsmentioning
confidence: 99%
“…2021; Wang et al. 2021). Interestingly, when the porosity of porous medium decreases below a critical value, the emergence of unstable invasion associated with rough invasion fronts and occurrence of trapping events is observed, which is reminiscent of invasion percolation (or capillary fingering in drainage condition).…”
Section: Introductionmentioning
confidence: 99%
“…In regular porous media – e.g. two-dimensional micromodels composed of circular posts with narrow particle size distribution arranged on a triangular or square lattice – both simulations and experiments have shown compact and faceted patterns (Cieplak & Robbins 1990; Martys, Robbins & Cieplak 1991; Holtzman 2016; Wang, Pereira & Gan 2021). This phenomenon was attributed to the dominance of the underlying pore geometry (regular lattice structure), which results in the symmetrical growth of invasion patterns.…”
Section: Introductionmentioning
confidence: 99%
“…However, when heterogeneity is introduced to particle shape (Wang et al. 2021), size (Lenormand 1990; Holtzman 2016; Hu et al. 2019) or position (Wang et al.…”
The unstable fluid–fluid displacement patterns in porous media with rough invasion fronts and trapping of the defending phase are often observed in drainage, i.e. when the solid is non-wetting to the invading phase. On the other hand, during imbibition, compact and faceted growth is expected in regular porous media with geometrically homogeneous pore structure. Here, we report the irregular growth of invading fluid during the imbibition process in two-dimensional regular porous media. The ramified invasion morphology associated with thin fingers is reminiscent of capillary fingering. Through examining the capillary pressure signals and the type of pore-scale invasion mechanisms, the fundamental differences between faceted growth and irregular invasion are revealed. By analysing the pore-scale invasion mechanisms, a phase diagram describing the dominance of different invasion events is proposed. Through conducting systematic quasi-static radial injection simulations across a wide range of porosity and wettability, excellent agreement is observed on the transition boundary from faceted and compact displacement patterns to irregular and dendritic invasion morphologies. This is reflected by the overlap of the transition boundaries from analytical prediction, type of pore-scale invasion events, and macroscopic morphology quantified by the fractal dimension. This work provides new insights on the role of geometrical features of solid structures during multiphase flow with emphasis on the porosity and wettability. The findings could assist in guiding the design of microfluidic devices to control deterministically the multiphase flow, transport and reaction processes.
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