ABSTRACT This study provides an exact analytical examination of the unsteady magnetohydrodynamic (MHD) natural convection flow of a viscous, incompressible, and electrically conducting fluid through a porous medium, past an exponentially accelerated inclined plate. The novelty of this research lies in the simultaneous consideration of thermal stratification, an inclined magnetic field, thermal radiation, chemical reactions, and a heat source—a combination not collectively examined in previous studies. The governing equations are solved for using the Laplace transform method. Closed‐form expressions for velocity, temperature, and concentration profiles are derived and analyzed in relation to key physical parameters. The analysis shows that thermal stratification lowers both the velocity and temperature fields while raising the wall shear stress and heat transfer rates. In particular, skin friction and the Nusselt number increase by and , respectively, compared to the non‐stratified case. Additionally, increasing the angle of inclination of the applied magnetic field improved the temperature profile but reduced the heat transfer rate. These findings highlight the critical influence of thermal stratification and magnetic inclination on MHD flow behavior, with potential applications in thermal management systems, geophysical convection, and magnetically controlled transport processes.

Conventional hydrochloric acid (HCl) acidizing in carbonate reservoirs is often limited by excessively rapid acid–rock reactions and preferential flow through high-permeability paths, resulting in shallow penetration and inefficient stimulation. Viscoelastic surfactant (VES)-based diverting acids have been widely applied to address these challenges; however, the intrinsic relationship between reaction retardation and diversion efficiency, particularly under varying shear conditions, remains insufficiently clarified. In this study, a VES-based diverting acid system formulated with erucamidopropyl hydroxysultaine (EH50) was systematically investigated through multiscale experiments, including rotating disk reaction kinetics, rheological characterization, porous core flooding, and fracture-scale plate flow tests. The results reveal a pronounced shear-dependent transition in the governing mechanism of the system. Under low-shear conditions, the VES system significantly reduces the apparent acid–rock reaction rate, with a maximum reduction of 77.3%, and exhibits a synergistic retardation effect in the presence of Ca2+, indicating mass transfer limitation. However, under high-shear porous media flow, the intrinsic retarding effect is substantially weakened due to partial disruption of the viscoelastic structure. Despite this attenuation of chemical retardation, effective diversion performance persists under dynamic flow conditions, manifested by pressure plateau behavior, enhanced flow redistribution, more distributed wormhole networks, and greater overall dissolution. Fracture-scale experiments further demonstrate that the diversion acid suppresses excessive inlet etching and promotes spatially distributed etching patterns favorable for fracture conductivity maintenance. These findings clarify that reaction retardation and diversion are distinct yet dynamically coupled mechanisms, whose relative dominance depends on shear intensity and ionic environment. The proposed shear-responsive mechanism framework provides new insight into the design and optimization of VES diverting acid systems for carbonate reservoir stimulation.

PINN-based numerical modeling of MHD flows in porous media over linear stretching boundaries

A diffuse interface model and fully decoupled, energy-stable scheme for the two-phase ferrofluid flows in porous media

Pore-scale visualization and microscale barrier mechanisms of microplastics transport in bio-based hydrogel modified soils.

Method of distributions for transient flow in porous media with uncertain properties

Research on doubly adaptive artificial compression algorithm for coupling model of incompressible flow and porous media flow

As a nonlinear advection-diffusion equation, the Richards equation poses considerable challenges for numerical approximation in saturated/unsaturated porous media flow. The lack of efficient, high-precision linearized schemes stems from theoretical difficulties caused by degeneracy and strong nonlinearity. In this work, we propose a three-level BDF2 finite element scheme with nearly second-order accuracy, providing detailed stability and convergence analysis. Numerical tests further confirm the theoretical results.

Chemical gradients are ubiquitous in porous media flows, from tidal salt gradients in aquifers to irrigation-driven gradients in soils and ionic gradients from metabolic activity in tissues. Although chemical gradients are known to drive diffusiophoretic migration of colloids, these nonequilibrium forces have largely been ignored in porous media flows. Under typical subsurface conditions, flow velocities within preferential pathways exceed phoretic velocities by orders of magnitude, suggesting that diffusiophoresis would be limited to stagnant pockets. Here, using microfluidic experiments, numerical simulations, and theoretical modeling, we show that even moderate solute gradients, typical of natural mixing, can markedly alter colloid transport. We uncover a previously overlooked effect: cross-streamline phoretic migration within preferential flow pathways, which changes macroscopic dispersion by orders of magnitude and suppresses the impact of geometric disorder on transport. Our findings challenge classical models of colloid transport, highlighting the broad implications of solute gradients for technological, biomedical, and environmental applications.

We investigate the entropy generation and streaming potential in the electroosmotic flow of a couple stress fluid through a slowly varying rotating microchannel. We examine the influence of an external magnetic field, porous permeability, and the Coriolis force on flow characteristics and entropy generation. The study employs a combination of semi-analytical and finite difference numerical methods to solve the governing equations associated with the current model. We present graphical analyses of velocity and temperature distributions, entropy generation, and Bejan number profiles to evaluate irreversibility and heat transfer rates. Furthermore, this study estimates the electrokinetic energy conversion efficiency from electrical double layer (EDL) ions to power generation. The electrokinetic energy conversion improves when the EDL is thicker, the porous medium has higher permeability, and the rotational speed increases. Conversely, the magnetic field reduces energy conversion. Higher values of the couple stress parameter and porous parameter contribute to increasing the Bejan number, whereas the Joule heating and the magnetic field have a reversal effect. The axial streaming potential rises with greater electroosmotic parameters and rotation speeds. These findings enhance understanding of the thermodynamic behavior of couple stress fluids in various engineering applications, such as electroosmotic flow in microchannels and porous media.

Wettability determination is of crucial importance for multiphase flow in porous media. Currently available methods are either applied to simplified geometries (sessile drop) or are time-consuming (Amott, USBM) and cost-intensive (micro-CT scanning). The purpose of this study is to systematically test the streaming potential method as a fast, cheap, and in situ applicable method for surface probing and determination of the wetting state of soda lime glass beads through zeta potential. Different wetting states are achieved by means of silanization and are characterized by an average contact angle. Comparison of contact angles measured by sessile drop on plate geometries and contact angles derived from bead pack micro-CT images confirmed that the treatment is transferable to the bead packs. The correlation between the zeta potential of the single bead size packing with a single wetting state and the contact angle is non-unique over the entire range of tested treatment volume ratios. The contact angle plateaus at higher degrees of silanization, while the zeta potential values still change. Before the plateau, a correlation between contact angle and zeta potential is present. Zeta potential measurements on the mixtures of the same-sized beads with two different wetting states confirm the existing theory that the apparent zeta potential is a surface area-weighted average of constituents. For a mixture where the zeta potential is size dependent, a new correlation for a dual bead system was derived. The non-unique correlation between zeta potential and contact angle, combined with a bead size-dependent zeta potential, will limit the use of zeta potential for contact angle derivation for the system of soda lime glass beads with various silanization coatings used here. Monitoring relative changes of wetting conditions might still be possible.

Analysing the uncertain impact of Brownian motion and thermophoresis on micropolar hybrid nanofluid flow in porous media through parallel rotating channels

This study investigates the steady magnetohydrodynamic flow of the Walter-B ternary nanofluid (composed of water-ethylene glycol (WEG) base fluid with graphene, alumina, and titanium dioxide nanoparticles) over a nonlinear stretching sheet, incorporating the effects of cross-diffusion, couple stress, and viscous dissipation. Using similarity transformations, the governing equations are converted to ordinary differential equations and solved numerically with MATLAB's bvp4c solver. A Bayesian-regularized artificial neural network (BRANN) is developed to predict skin friction, Nusselt, and Sherwood numbers with R² > 0.99 accuracy. Results reveal that fluid velocity decreases with increasing couple stress but enhances with the Deborah number and Darcy parameter, while temperature rises with the Eckert and Dufour numbers. Concentration profiles decline with chemical reaction but grow with the Soret number. Entropy generation intensifies with Brinkman and Biot numbers, whereas the Bejan number shows opposite behavior. Empirical correlations for skin friction, Nusselt, and Sherwood numbers are developed, showing a 6.3% rise in skin friction with the Forchheimer number and a 13.14% improvement in heat transfer with thermal radiation. This work provides critical insights for thermal management systems, leveraging machine learning to optimize ternary nanofluid flows in porous media under cross-diffusion effects.

From interface dynamics to Darcy scale description of multiphase flow in porous media.

The role of phase topology in hysteresis during fluid injection and withdrawal in porous media is not fully understood. We address this by providing experimental and theoretical evidence on three key findings. (1) The topological evolution of the nonwetting fluid is distinct from the capillary pressure and the specific interfacial area, as shown by experiments and a generalized model. (2) Saturation paths with identical capillary pressure and interfacial area show different topologies, revealing insights into energy dissipation and phase connectivity. (3) The topological evolution of the nonwetting phase follows predictable trajectories captured by a piecewise non-linear model. These findings offer practical implications for optimizing subsurface hydrogen and carbon dioxide storage systems and provide a novel approach to study complex systems with topological singularities.

A numerical evaluation of hydrate reformation risk during gas flow in porous media

Surrogate modeling for three-phase flow in porous media based on a temporal-attention-enhanced multiple-input operator network

Monte Carlo simulation of apparent permeability for shale gas flow in three-dimensional fractal porous media

Well-posedness and numerical simulations of a reactive flow in a heterogeneous porous medium

ABSTRACT The mechanisms of CO2 Miscible Front Migration is a key factor for enhanced oil recovery in CO2 flooding, it is difficult to be described due to complex interactions between fluids, therefore, the CO2 Miscible Front Migration characteristics are unclear. In this paper, we established an injection-production pair model for coupled Gas-Oil Two-Phase Flow in Miscible Flooding based on the theory of Fluid Interactions in Miscible Flooding and gas-oil two-phase fluid flow in porous media, considering the heterogeneity, reservoir dip angle and miscibility degree. The results show that with the increase in gas viscosity, dip angle and decrease of intralayer heterogeneity, the gas breakthrough time is later and the distance of miscible front migration is longer; With the increase of interlayer heterogeneity and reservoir pressure, the gas breakthrough time is earlier and the distance of miscible front migration is shorter. At the same time, due to the negligence effect between CO2 and oil, and well pattern in the analytical model, an ideal model based on reservoir parameters from Block G66 × 1 fault-block reservoir in Jidong Oilfield is established. The model identified the CO2-crude oil miscible zone by using oil saturation and CO2 molar fraction in oil and characterized the migration patterns of the CO2 miscible front through bottom-hole pressure, gas-oil ratio, and dynamic front-position monitoring. Simulation results show when areal heterogeneity increases from 1 to 9, CO2 breakthrough time is earlier, the contribution of the pure oil flow zone to recovery factor decreased from 72.62% to 26.31%, the contribution of CO2 mass transfer zone to recovery factor increased from 14.06% to 47.11%. When the formation dip angle increased from 0° to 35°, CO2 breakthrough time is earlier, the contribution of the pure oil flow zone to recovery factor increased from 59.32% to 65.62%, the contribution of CO2 mass transfer zone to recovery factor decreased from 17.54% to 16.32%. With initial water saturation increasing from 50% to 90%, displacement efficiency continued decreasing, CO2 flooding breakthrough time is later. The contribution of the pure oil flow zone to recovery factor increased from 55.68% to 82.58%, and the contribution of CO2 mass transfer zone to recovery factor decreased from 27.42% to 10.20%. The results provide the basis for front prediction and control in CO2 miscible flooding development.