Alexander Scheuermann

Discovery of Dynamic Two-Phase Flow in Porous Media Using Two-Dimensional Multiphase Lattice Boltzmann Simulation

Publisher: MDPI AG

Date: 05-07-2021

DOI: 10.3390/EN14134044

Abstract: The dynamic two-phase flow in porous media was theoretically developed based on mass, momentum conservation, and fundamental constitutive relationships for simulating immiscible fluid-fluid retention behavior and seepage in the natural geomaterial. The simulation of transient two-phase flow seepage is, therefore, dependent on both the hydraulic boundaries applied and the immiscible fluid-fluid retention behavior experimentally measured. Many previous studies manifested the velocity-dependent capillary pressure–saturation relationship (Pc-S) and relative permeability (Kr-S). However, those works were experimentally conducted on a continuum scale. To discover the dynamic effects from the microscale, the Computational Fluid Dynamic (CFD) is usually adopted as a novel method. Compared to the conventional CFD methods solving Naiver–Stokes (NS) equations incorporated with the fluid phase separation schemes, the two-phase Lattice Boltzmann Method (LBM) can generate the immiscible fluid-fluid interface using the fluid-fluid/solid interactions at a microscale. Therefore, the Shan–Chen multiphase multicomponent LBM was conducted in this study to simulate the transient two-phase flow in porous media. The simulation outputs demonstrate a preferential flow path in porous media after the non-wetting phase fluid is injected until, finally, the void space is fully occupied by the non-wetting phase fluid. In addition, the inter-relationships for each pair of continuum state variables for a Representative Elementary Volume (REV) of porous media were analyzed for further exploring the dynamic nonequilibrium effects. On one hand, the simulating outcomes reconfirmed previous findings that the dynamic effects are dependent on both the transient seepage velocity and interfacial area dynamics. Nevertheless, in comparison to many previous experimental studies showing the various distances between the parallelly dynamic and static Pc-S relationships by applying various constant flux boundary conditions, this study is the first contribution showing the Pc-S striking into the nonequilibrium condition to yield dynamic nonequilibrium effects and finally returning to the equilibrium static Pc-S by applying various pressure boundary conditions. On the other hand, the flow regimes and relative permeability were discussed with this simulating results in regards to the appropriateness of neglecting inertial effects (both accelerating and convective) in multiphase hydrodynamics for a highly pervious porous media. Based on those research findings, the two-phase LBM can be demonstrated to be a powerful tool for investigating dynamic nonequilibrium effects for transient multiphase flow in porous media from the microscale to the REV scale. Finally, future investigations were proposed with discussions on the limitations of this numerical modeling method.

Study on filtration process of geotextile with LBM-DEM-DLVO coupling method

Publisher: Elsevier BV

Date: 02-2021

DOI: 10.1016/J.GEOTEXMEM.2020.09.011

Salt Transport Under Tide and Evaporation in a Subtropical Wetland: Field Monitoring and Numerical Simulation

Publisher: American Geophysical Union (AGU)

Date: 29-04-2022

DOI: 10.1029/2021WR031530

Abstract: Tidal wetland ecosystems are sensitive to porewater salinity dynamics. However, it is unclear how salts move and distribute in these wetlands, particularly how the salts accumulated by evaporation get removed from the wetland soil, so that the salinity levels may stabilize to accommodate vegetation. We conducted a combined field and modeling study to identify the porewater flow and salinity patterns in a subtropical wetland subjected to tidal inundation and evaporation. Measured and simulated salinity contours indicated the formation of hypersaline porewater plumes in the upper intertidal zone and the fresher porewater zones with salinity close to that of seawater near the creek and in the supratidal zone. Simulations indicated the discharge of the hypersaline upper intertidal porewater to the creek with a discharge pathway developed under the fresher near‐creek porewater zone, and this was further confirmed by the field‐observed significant salinity gradient under the creek. Our model suggested that both water and salt discharge from the wetland soil occurred predominantly at the creek bank and creek bed. The porewater discharge is more intensive through the creek bank than the creek bed, while the salt discharge across both the creek bank and creek bed was comparable due to the much higher salinity level under the creek bed. Salt discharge driven by density gradients and tidal‐induced porewater circulation provides a mechanism for removing salts accumulated in the upper intertidal zone due to evaporation and could prevent salt flat formation and marsh plants dieback.

Mesoscopic model framework for liquid slip in a confined parallel-plate flow channel

Publisher: American Physical Society (APS)

Date: 22-03-2021

DOI: 10.1103/PHYSREVFLUIDS.6.034203

Influence of hydraulic and geometric conditions on the early stages of the filtration process in idealised granular soils comprising spherical particles

Publisher: Wiley

Date: 02-06-2023

DOI: 10.1002/NAG.3583

Abstract: The early stages of particle‐scale filtration in idealised granular soils were investigated using coupled Computational Fluid Dynamics and Discrete Element Method. Filtration simulations were conducted for assemblies of finer base particles underlying coarser filter particles with upward seepage flow perpendicular to the base‐filter interface. A wide range of size ratios that covered the complete spectrum of filtration behaviours were considered, along with different r ing accelerations for seepage flow to investigate the combined influence of geometric characteristics and hydraulic loading. The influence of flow conditions and size ratios on the time‐dependent infiltration depth of transported base particles was observed to be universal with respect to a newly proposed dimensionless time parameter. The susceptibility to filtration during the early stages was quantitatively investigated with the number of infiltrating base particles and the filling degree of pores within the filter. The susceptibility during the early stages was shown to have a strong correlation with pore space geometry at the filter boundary, which was also reflected by the maximum pore filling degree of the filter. While filter susceptibility has been conventionally evaluated by the size ratio of the assembly, the consideration of the pore space geometry at the filter boundary provided an alternate approach of evaluating local filter susceptibility.

The importance of initial particle position on filter performance in granular soils

Publisher: Elsevier BV

Date: 10-2023

DOI: 10.1016/J.COMPGEO.2023.105632

Spatial and Temporal Evolution of Particle Migration in Gap-Graded Granular Soils: Insights from Experimental Observations

Publisher: American Society of Civil Engineers (ASCE)

Date: 03-2023

DOI: 10.1061/JGGEFK.GTENG-11094

Applying Imaging Technique to Investigate Effects of Solute Concentrations and Gas Injection Rates on Gas Bubble Generation

Publisher: Hindawi Limited

Date: 11-10-2022

DOI: 10.1155/2022/2046267

Abstract: This work investigated the bubble size variation under various aqueous conditions, including saline and surfactant solutions, with different gas injection rates using a commercial bubble analyzer. The results show that salt and surfactant can minimize bubble size with increasing solute concentration, and the surfactant outperforms salt. In addition, the critical coalescence concentrations (CCC) of salt and surfactant could be determined at 20 g/l and 20 mg/l, respectively, over which bubble mean size cannot be further reduced. On the other hand, the gas injection rate, compared to the solute concentration, has minor effects on bubble size variation. Nonetheless, there is a critical coalescence injection rate (CCIR) of 30 ml/min for surfactant solution, over which the standard deviation of the bubble size distribution (BSD) cannot be further increased. In principle, this work improves the accuracy and efficiency of the bubble analyzer. It also presents a sound understanding of two influential factors rather than a single-factor controlling bubble size. Most importantly, it is the first time to observe and propose the concept of CCIR to describe how the gas injection rate influences the standard deviation of BSD. Based on those results and findings, it is able to conclude that bubble size control, whose mechanism has been previously identified as the bubble collision and coalescence rather than the surface tension of water solutions, is actually dominated by not only the solute concentration but also the gas injection rate when a porous air sparger is used to generate bubbles. It is expected that this work could contribute to laboratory modeling bubbly flow in a porous medium in order to bring more insights into the mechanism of soil gas leaking through soil strata.

ARC Future Fellowships - Grant ID: FT180100692

Start Date: 09-2018

End Date: 12-2023

Amount: $1,000,125.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP120100662

Start Date: 11-2012

End Date: 11-2015

Amount: $377,800.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100130

Start Date: 2015

End Date: 06-2017

Amount: $320,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP120102188

Start Date: 2012

End Date: 12-2017

Amount: $490,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100058

Start Date: 04-2015

End Date: 11-2018

Amount: $560,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100011

Start Date: 01-2012

End Date: 12-2012

Amount: $700,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP160101066

Start Date: 03-2017

End Date: 12-2021

Amount: $365,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140100490

Start Date: 2014

End Date: 12-2017

Amount: $660,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100028

Start Date: 06-2013

End Date: 12-2014

Amount: $300,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110201102

Start Date: 12-2011

End Date: 12-2014

Amount: $230,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE160100206

Start Date: 06-2016

End Date: 06-2018

Amount: $800,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180104156

Start Date: 01-2018

End Date: 12-2022

Amount: $446,340.00

Funder: Australian Research Council