Transport in Porous Media最新文献

This is a commemoration of the work of Don Nield. His theoretical and applied mathematical models have had a tremendous impact in many fields including convection heat and mass transfer, stability analysis, nanofluid enhanced convection, and flows in porous media.  Here the major contributions of Don Nield’s Scopus-indexed outputs are reviewed. His research outputs and related impact are presented chronologically. The citation counts are presented with respect to each work published in that year. The work and impact of Don Nield as single author and in his collaborations are presented.

The study intends to investigate the effects of fluid characteristics on the Darcian flow through porous media, which would help to perceive the merits of its employment in different designs of porous media systems. To systematically conduct this aim, both theoretical modeling and numerical simulations are used while using different incompressible fluids of four liquids (water, oil, n-heptane, and n-hexane) and three gases (nitrogen, carbon dioxide, and methane). In this regard, an acceptance between the simulation results and the experimental findings is confirmed. The results demonstrate the actual effect of friction factor and pressure gradient on the fluid properties of viscosity and density. An increase in Reynolds numbers caused a decrease in the friction factor, which signify a shift in dominance from viscous to inertial forces. The pressure gradient rises with higher inlet velocities, proposing that a higher flow rate necessitates a larger pressure differential to overwhelmed resistance of the porous structure.

Reactive transport modeling in unique chamosite, illite, and kaolinite monomineralic clay reservoirs was performed to predict spatial and mineralogical control on H_2(aq) distribution and flow dynamics at simulated underground hydrogen storage pressure and temperature conditions in high permeability depleted oil reservoirs and lower permeability sandstones. Results are normalized against simulations performed in pure quartz for comparative purposes and to serve as a benchmark for H₂ storage in sandstone or quartz-arenite reservoirs. Isobaric and isothermal condition results indicate that Péclet numbers increase with volume rate of injected fluid. Advection-mediated transport is ubiquitous for injection rates between 0.01 and 1.0 L per second, although diffusion-mediated transport is prevalent in the center of the RMT block at 0.001 L per second injection. Source/sink term and Péclet number analysis indicate that the effect of mineralogy on H_2(aq) transport is small. Flow velocities in kaolinite are typically the fastest, but chamosite Péclet numbers are greatest. This suggests that kaolinite favors diffusion, chamosite favors advection, and illite is intermediate. A more accurate reflection of underground hydrogen storage conditions incorporating temperature and pressure gradients, permeability anisotropy, and mineralogical heterogeneity shows a decrease in Péclet numbers proportional to distance from injection well. Thus, along the reservoir-caprock boundary and in the absence of cushion gas, H_2(aq) loss through diffusion is probable. Although quantitative flow regime analysis cannot be determined at many grid point locations due to uniform H_2(aq) concentration, these locations are very likely diffusion dominant.

Macroscopic models of inertial flows in porous media have many practical applications where direct numerical simulations are not feasible. The Forchheimer equation describes macroscopic momentum transport accounting for inertial effects at the pore scale through a nonlinear correction tensor ({textbf{F}}_beta) to the permeability. The goal of this work is to study the effects of inertial flow orientation on the Forchheimer correction. Using up-scaling approaches such as the volume averaging method, ({textbf{F}}_beta) can be determined. However, the procedure requires to deal with a nonlinear problem for the deviations of the local velocity field. This is commonly tackled by assuming that the inertial convective velocity is decoupled from the velocity deviations. Here, we propose an alternative approach based on regular perturbation expansion leading to a series of linear closure problems. The values of ({textbf{F}}_beta) predicted by both approaches are compared for various values of the Reynolds number and flow orientation. Compared to the local inertial–convection approach, the proposed linearized closure problem has the advantage of being self-consistent, independent of the pore Reynolds number and of flow orientation. It is, however, limited in validity by Reynolds number below one and requires the solution of closure problems of higher dimensions. Then, macroscopic simulations are performed to evaluate the importance of varying pressure gradient orientation on the macroscopic inertial flow. Numerical results of the general macroscopic model obtained by the volume averaging method highlight the necessity to account for extra-diagonal terms as well as macroscopic gradient orientation in the determination of the Forchheimer tensor.

This article investigates thermal convection in Kelvin–Voigt fluids saturating a Brinkman–Darcy-type porous medium under variable gravity effects. The stability analysis encompasses linear, nonlinear conditional, and nonlinear unconditional regimes, leveraging the generalized Maxwell–Cattaneo law for heat flux. Normal mode technique is applied for linear analysis, while nonlinear governing equations for conditional and unconditional stability are derived using energy methods. The compound matrix method is utilized to compute critical Rayleigh numbers and corresponding wave numbers. Numerical computations are performed in MATLAB to determine all critical values, with graphical results illustrating stability trends. Six gravity variation profiles are examined, revealing that the gravity modulation parameter (epsilon) influences stability depending on the gravity profile, either promoting or suppressing convection. Additionally, the parameter (xi) consistently enhances stability by increasing the critical Rayleigh numbers across all cases. These findings highlight the role of gravity variations and material parameters in shaping convection onset, contributing to a deeper understanding of thermal stability in viscoelastic porous systems.

A joint experimental and numerical study is presented to close the current gap in fully coupled data and modeling capabilities for self-pumping transpiration cooling (SPTC). An experimental setup was developed to investigate the effects of the porous medium properties, the flow conditions, and the interactions between solid and coolant on SPTC. Additionally, a two-reference-point, locally emissivity-corrected evaluation methodology for analyzing infrared (IR) measurements was developed, which is valid for quasi-steady evaporation regimes and achieves a better repeatability. For the numerical simulations, we developed an upscaling workflow with pore-network models derived from micro computed tomography (CT) data to accurately describe effective representative elementary volume (REV)-scale parameters and relations. Using upscaled properties, we created a non-isothermal, two-phase Darcy-scale model for the porous medium and modeled free-flow with Reynolds-averaged Navier–Stokes equations, employing an shear stress transport (SST) (ktext {-}omega) turbulence closure to capture near-wall shear stress effects. Coupling conditions ensured mass, momentum, and energy transfer at the interface. The experimental results show a high reproducibility and new insights for the surface temperature at SPTC with the new IR method. The comparison between experimental and numerical results show good agreements. The developed simulation workflow is a major step toward creating a digital twin of an experimental SPTC system. This work lays the foundation for investigating the influence of parameters on SPTC systems and optimizing their efficiency.

The emergence of micro-computed tomography has significantly enhanced our ability to examine the morphology of porous materials and the dynamics of fluid flow within pore spaces. However, image-based analyses can be compromised by various artifacts, particularly ring artifacts, which appear as concentric rings in the images. These artifacts can be misinterpreted as part of the pore space, artificially connecting pores and thus influencing numerical simulations. This study examines the influence of ring artifacts on pore network modeling (PNM), direct numerical simulation (DNS), and prominent numerical techniques, and presents a computing approach for their effective mitigation. For this purpose, a dataset was compiled from the literature that includes the images of Fontainebleau, Boise, and Belgian sandstones. Data augmentation was implemented by extracting real ring patterns from Fontainebleau samples and superimposing them onto clean images of the sandstones. Two U-Net autoencoder architectures (base and Attention U-Net) were trained for a regression task aimed at removing ring artifacts while reconstructing the underlying pore morphologies. The Attention U-Net outperformed the base model, achieving a mean squared error of 0.07 (calculated based on the grayscale values between 0 and 255). Visual evaluations confirmed the model’s effectiveness in artifact removal and pore morphology reconstruction. The model was further tested on unseen pore-scale data containing real ring artifacts, which indicated a high performance in removing the artifacts. DNS and PNM were performed on both original (with real rings) and improved 3D samples (200³ voxels) to assess the impact of artifact removal on transport properties. The results revealed that ring artifacts, identified as flow pathways, significantly influence the velocity profiles. While the presence of the artifact had a minimal effect on porosity (a 1.68% error) and the number of pores (1.45% error), it significantly increased the permeability by 34%.

Graphical Abstract

We develop an innovative mixed-dimensional 3D/1D flow model in carbonate rocks containing multiple karst cave conduits with underlying heterogeneity in the petrophysical properties stemming from different geological stages of cave-pipe collapse systems. Such geological structures manifest in distinct heterogeneity patterns inherent to the successive stages of burial, mechanical failure, and collapse, resulting in discrete collapsed passages in the conduit network. In addition, breakdown products appear within the cave system associated with chaotic breccia, suprastrata deformation, and vertical tube-like geo-bodies, herein referred to as breccia pipes, containing faults and fractures around the vertical pipe. The input parameters of the mixed-dimensional flow model show the ability to incorporate the complex multiple heterogeneities associated with the geological objects at different stages of collapse. After populating the geo-bodies with proper petrophysical properties, the mixed-dimensional flow equations are discretized by a locally conservative extended version of the mixed-hybrid finite element method, which incorporates the new nonlinear discrete transmission jump conditions between elements adjacent to the breccias within the conduits. Computational simulations are performed for particular configurations of heterogeneous karst conduit systems with distinct geological time scales, illustrating the influence of the karst and solution breccia-pipe deposits upon the flow regimes, streamline patterns, and well productivity in real-case scenarios of hypogenic cave networks.

This study deals with the thermal gravitational convection of a variable viscosity fluid in a closed two-dimensional cavity in the presence of a porous layer. In addition, at the lower edge of the region there is a heat-conducting energy source with periodic heat release. The problem has been solved in dimensionless non-primitive parameters including stream function and vorticity using the finite difference schemes on a uniform structured mesh. The influence of the defining characteristics of heat transfer such as the Darcy and Rayleigh numbers, the height of the porous layer, the heater location, as well as the frequency of the heat dissipation from the heater, has been studied. The results have been demonstrated using isolines of the stream function and temperature combined with time dependences of the integral characteristics of heat transport for various values of dimensionless parameters. The conclusions obtained have demonstrated that the periodic nature of heat dissipation completely determines the periodicity of convective processes in the cavity. In addition, the presence of a porous layer and the ability to change the position of the heater make it possible to control heat removal.