Flow In Media Research Articles

Review of the Color Gradient Lattice Boltzmann Method for Simulating Multi-Phase Flow in Porous Media: Viscosity, Gradient Calculation, and Fluid Acceleration

Review of the Color Gradient Lattice Boltzmann Method for Simulating Multi-Phase Flow in Porous Media: Viscosity, Gradient Calculation, and Fluid Acceleration

Chiral Separation Enhancement in Capillary Electrophoresis by Electrophoretic Mobility Differences without Electroosmosis.

To improve separation efficiency and address the adverse effects of electro-osmosis, a coated capillary was used to shield the electroosmosis. A nanoflow pump was used to control the flow of the electrophoretic medium, thereby extending the time of the electrophoretic action. Furthermore, by using a coated capillary that is only 10 cm long as the separation column, the electric field strength could reach as high as 250 V/mm. These strategies strengthened the interaction between the enantiomers and the chiral selector, thus enhancing the resolution of enantiomers. As a result, complete separation of the amlodipine enantiomers could be achieved by halting the electrophoretic medium. Further extending the duration of flow stoppage can increase the resolution several-fold. The method established in this study exhibits excellent accuracy and precision. Despite experiencing a long period of flow stoppage, the relative standard deviations of both migration time and resolution remain less than 2%. This method not only remarkably enhanced the resolution of amlodipine enantiomers but also demonstrated broad applicability in separating other chiral enantiomers, particularly for those substances that are difficult to separate using conventional capillary electrophoresis.

A Numerical Investigation of Sinusoidal Flow in Porous Media with a Simple Cubic Beam Structure at 1 Hz and 100 Hz Under Different Porosity Conditions

This study aims to clarify how porosity and frequency interact to influence permeability and flow behavior in porous media subjected to sinusoidal pressure variations. Specifically, we investigate oscillatory flow at 1 Hz and 100 Hz under varying porosity conditions using a pore-scale Computational Fluid Dynamics (CFD) model. The model is validated against the Johnson–Koplik–Dashen (JKD) model to ensure accuracy in capturing dynamic permeability. At 1 Hz, where the oscillation period greatly exceeds the system’s time constant τ, the flow reaches a quasi-steady state with dynamic permeability approximating static permeability. Increasing porosity enhances Darcy velocity, with minimal phase difference between velocity and pressure. At 100 Hz, flow behavior depends on the ratio of the oscillation period T to τ. For high porosity (φ=0.840, T≈τ), the flow does not fully develop before the pressure gradient reverses, leading to significant phase lag. For low porosity (φ=0.370, T≈12τ), the phase lag is smaller but remains non-zero due to the smooth temporal variation in pressure. This work contributes to the understanding of porous flow dynamics by revealing how porosity modulates both the amplitude and phase angle of dynamic permeability in frequency-dependent porous flows, providing a framework for predicting phase lag in frequency-sensitive applications.

Large-Time Behavior of Solutions to Darcy–Boussinesq Equations with Non-Vanishing Scalar Acceleration Coefficient

We study the large-time behavior of solutions to Darcy–Boussinesq equations with a non-vanishing scalar acceleration coefficient, which model buoyancy-driven flows in porous media with spatially varying gravity. First, we show that the system admits steady-state solutions of the form (u,ρ,p)=(0,ρs,ps), where ρs is characterised by the hydrostatic balance ∇ps=−ρs∇Ψ. Second, we prove that the steady-state solution satisfying ∇ρs=δ(x,y)∇Ψ is linearly stable provided that δ(x,y)<δ0<0, while the system exhibits Rayleigh–Taylor instability if Ψ=gy, ρs=δ0g and δ0>0. Finally, despite the inherent Rayleigh–Taylor instability that may trigger exponential growth in time, we prove that for any sufficiently regular initial data, the solutions of the system asymptotically converge towards the vicinity of a steady-state solution, where the velocity field is zero, and the new state is determined by hydrostatic balance. This work advances porous media modeling for geophysical and engineering applications, emphasizing the critical interplay of gravity, inertia, and boundary conditions.

Stable Multipoint Flux Approximation (MPFA) Saturation Solution for Two-Phase Flow on Non-K-Orthogonal Anisotropic Porous Media

This paper extends the multipoint flux approximation (MPFA-O) method to model coupled pressure and saturation dynamics in subsurface reservoirs with heterogeneous anisotropic permeability and non-K-orthogonal grids. The MPFA method is widely used for reservoir simulation to address the limitations of the two-point flux approximation (TPFA), particularly in scenarios involving full-tensor permeability and strong anisotropy. However, the MPFA-O method is known to suffer from spurious oscillations and numerical instability, especially in high-anisotropy scenarios. Existing stability-enhancing techniques, such as optimal quadrature schemes and flux-splitting methods, mitigate these issues but are computationally expensive and do not always ensure monotonicity or oscillation-free solutions. Building upon prior advancements in the MPFA-O method for pressure equations, this work incorporates the saturation equation to enable the simulation of a coupled multiphase flow in porous media. A unified framework is developed to address stability challenges associated with the tight coupling of pressure and saturation fields while ensuring local conservation and accuracy in the presence of full-tensor permeability. The proposed method introduces stability-enhancing modifications, including a local rotation transformation, to mitigate spurious oscillations and preserve physical principles such as monotonicity and the maximum principle. Numerical experiments on heterogeneous, anisotropic domains with non-K-orthogonal grids validate the robustness and accuracy of the extended MPFA-O method. The results demonstrate improved stability and performance in capturing the complex interactions between pressure and saturation fields, offering a significant advancement in subsurface reservoir modeling. This work provides a reliable and efficient tool for simulating coupled flow and transport processes, with applications in CO2 storage, hydrogen storage, geothermal energy, and hydrocarbon recovery.

Design of Ricker Wavelet Neural Networks for Heat and Mass Transport in Magnetohydrodynamic Williamson Nanofluid Boundary-Layer Porous Medium Flow with Multiple Slips

In the current paper, an analysis of magnetohydrodynamic Williamson nanofluid boundary layer flow is presented, with multiple slips in a porous medium, using a newly designed human-brain-inspired Ricker wavelet neural network solver. The solver employs a hybrid approach that combines genetic algorithms, serving as a global search method, with sequential quadratic programming, which functions as a local optimization technique. The heat and mass transportation effects are examined through a stretchable surface with radiation, thermal, and velocity slip effects. The primary flow equations, originally expressed as partial differential equations (PDEs), are changed into a dimensionless nonlinear system of ordinary differential equations (ODEs) via similarity transformations. These ODEs are then numerically solved with the proposed computational approach. The current study has significant applications in a variety of practical engineering and industrial scenarios, including thermal energy systems, biomedical cooling devices, and enhanced oil recovery techniques, where the control and optimization of heat and mass transport in complex fluid environments are essential. The numerical outcomes gathered through the designed scheme are compared with reference results acquired through Adam’s numerical method in terms of graphs and tables of absolute errors. The rapid convergence, effectiveness, and stability of the suggested solver are analyzed using various statistical and performance operators.

Adolescent Interpersonal Communication Culture in Jakarta High School in the Smartphone Era

Using smartphones in interpersonal communication among adolescents is now commonplace. Many teenagers who follow the flow of communication media in technology choose smartphones as a more effective interpersonal communication medium. Compared to other forms of communication, interpersonal communication occurs personally, in face-to-face situations, and through media. Interpersonal communication is fundamental since it permits it to require place dialogic communication. Exchange may be a shape of interpersonal communication that appears in the event of interaction. Those included in this communication frame are double-functioning, each being the speaker and the audience, on the other hand. This report analyzes adolescents’ interpersonal communication culture in the smartphone-use era based on this statement. The method used is the phenomenological method. The conclusion of this study indicates that the current adolescent interpersonal communication culture is more influenced by digital technology than direct interaction. Therefore, efforts are needed to foster awareness of the importance of maintaining a healthy quality of interpersonal communication amid technological advances.

A non-uniform time-stepping method for time-fractional diffusion-wave equations with variable coefficients arising in fluid flow problems

Purpose The time-fractional diffusion-wave equation (TFDWE) models fluid flow in inhomogeneous media where transport phenomena exhibit anomalous diffusion processes, such as super-diffusive behavior seen in fusion plasmas, molecular movement in living cells and more. This paper aims to present two efficient schemes to solve TFDWE with spatially variable coefficients for non-smooth solutions having singularity at initial time t = 0. Design/methodology/approach To quantify the solution’s initial layer, the authors apply a half-point discretization process to the time domain on a non-uniform temporal mesh using the L1 finite difference scheme. Central and compact difference schemes are proposed subject to Dirichlet boundary conditions. The energy method is used to prove the stability and convergence of the proposed schemes. Furthermore, a central difference scheme is also presented to solve the two-dimensional (2D) TFDWE with variable coefficients for non-smooth solutions. Finally, numerical examples are presented to verify the convergence order and consistency of the proposed schemes. Findings The central and compact difference schemes achieve convergence orders O(N−(3−α)+h2) and O(N−(3−α)+h4), respectively, where N,α and h represent the number of temporal grids, order of the fractional derivative and spatial grid size, respectively. The results show that the compact difference scheme reduces the computational cost and storage requirement. Originality/value A high-order finite difference scheme is used to solve TFDWE in both 1D and 2D cases with variable coefficients. The spatial accuracy has improved using the compact difference scheme. In addition, the authors tested one example with an initial discontinuity for 1D and 2D cases.

Variable Temperature Plate Heat Transfer: MHD Fluid Natural Convection Flow in Porous Medium

The heat transfer from a variable temperature plate has been studied under the presence of porous medium and MHD fluid. Solutions for flat plate in porous medium are usually numeric, in this work an exact solution is found. Free convection governing equations were nondimensionalized and solved using Laplace transform. Exact solutions for the dependent non-dimensional variables were obtained. Velocity and temperature solutions that satisfy the governing equations and exponential boundary conditions were validated with a special case from the existing literature and found to be in good agreement. The temperature and velocity distributions within the porous medium were analysed for different non-dimensional numbers such as Prandtl number and Grashof number and for Newtonian and non-Newtonian fluids. It has been found that the Pr number decreases the velocity variation as a result of the increased viscosity. Higher Grashof number increases the velocity variation for the extra potential it supplies in the momentum equation. Heat generation term raises the dimensionless temperature variation in the energy equation, in its turn the dimensionless temperature increases the velocity variation.

Fractional analysis of time-fractional Emden–Fowler model arising in fluid flow of porous media and physical sciences

The concept of time-fractional Emden–Fowler (EF) model is used to describe the fluid flow in porous media, where the flow displays fractional-order behavior due to intricate microstructures. This study aims to analyze the fractional analysis of a linear and nonlinear time-fractional EF model, in which the fractional derivatives are taken in the Caputo form. We establish the Sumudu perturbation transform method (SPTM) by combining the Sumudu transform (ST) with the homotopy perturbation method (HPM). The ST discretizes the fractional-order model to a Sumudu space where the utilization of HPM handles the nonlinear parameters in the recurrence relation very effectively. We provide two numerical tests of the time-fractional EF model to check the legitimacy and reliability of the suggested scheme. The derived outcomes by SPTM enhance the excellence over a longer period by reducing the parameters of the truncated series. Some graphical representations at different fractional orders are provided to validate our proposed scheme. This approach offers a clear and concise procedure with symbolic computation to derive the series results which converge very promptly.

The role of phase interference in steady-state two-phase flow in porous media

The role of phase interference in steady-state two-phase flow in porous media

Cross-diffusion effects of viscous heating hydromagnetic Casson fluid flow in permeable vertical media with radiation and heat loss

Cross-diffusion effects of viscous heating hydromagnetic Casson fluid flow in permeable vertical media with radiation and heat loss

A comprehensive study of two-phase flow in deformable porous media

This study explored the initial-boundary value problem of an immiscible, incompressible two-phase flow within a deformable porous medium system, modeled in an N-dimensional (N≥3) Euclidean space. The primary objective was to devise a novel model that effectively captured previously overlooked physical phenomena and established the global existence of a weak solution to the system. After proving the existence of a classical solution to the approximate problem using Schauder's fixed point theorem under a series of reasonable assumptions, we obtained the convergence to a weak solution of the original problem in two different cases by applying the Fréchet–Kolmogorov theorem. Subsequently, we verified the applicability of this model to the commonly used van Genuchten model in the dynamic simulation of oil storage, providing theoretical support for engineering applications.

A universal structure of neural network for predicting heat, flow and mass transport in various three-dimensional porous media

A universal structure of neural network for predicting heat, flow and mass transport in various three-dimensional porous media

A class of high-order physics-preserving schemes for thermodynamically consistent model of incompressible and immiscible two-phase flow in porous media

A class of high-order physics-preserving schemes for thermodynamically consistent model of incompressible and immiscible two-phase flow in porous media

Coaxial bioprinting of a three-layer vascular structure exhibiting blood-brain barrier function for neuroprotective drug screening.

Coaxial bioprinting of a three-layer vascular structure exhibiting blood-brain barrier function for neuroprotective drug screening.

Effect of magnetic field on hydrodynamics of MRSTP media flow and material removal modelling of blade tenon

Effect of magnetic field on hydrodynamics of MRSTP media flow and material removal modelling of blade tenon

MICRO-HIDROTURBINE DE JOASĂ CĂDERE UTILIZATE PENTRU CREȘTEREA EFICIENȚEI SISTEMELOR DE IRIGAȚII ALIMENTATE DIN PANOURI FOTOVOLTAICE

This paper presents an improved solution for solar powered irrigation systems by integrating low-head micro-hydro turbines for energy recovery when discharging the water from the storage tank. The proposed solution is justified by the potential energy available when storing water in a tank using pumps powered by PV panels. This energy can be used to provide additional electricity when discharging the water, by placing a low-head micro-hydro turbine at the bottom of the tank. The energy produced can be used for pumping back a fraction of the consumed volume of water, or to ensure the pressure for longer distance irrigation networks. The energy surplus provided by the turbine is necessary especially when irrigating during mornings and evenings, when PV system power production is reduced. A low head micro-hydro turbine suitable for a small scale solar powered irrigation systems was tested on a dedicated testing stand in order to demonstrate its efficiency. The turbine was designed to generate 1 kW of power operating at 2.4 m head and 360 m3/h flow. The tested model reached a maximum output of 526 W at 2 m head and 240 m3/h flow. The rotor is made from thermoplastic by 3D printing, thus the flow through the turbine was limited to avoid damaging the blades. The experimental data was compared to the specific data of a small-scale solar powered irrigation system to determine the total efficiency of a hybrid irrigation system. The calculation takes into account the medium flow rate needed for turbine operation during irrigation phase, correlated with the electricity requirements of the pump for obtaining specific flows. The additional power output can increase the global efficiency of a solar powered irrigation system by feeding the electricity back to the pumping unit. For a PV power system that provides 20 kWh/day, the turbine can ensure around 22.5% of the energy needed for irrigation.

Numerical simulation of double-diffusive convection in hybrid nanofluid flow in a porous medium within a swastika-shaped cavity

Numerical simulation of double-diffusive convection in hybrid nanofluid flow in a porous medium within a swastika-shaped cavity

Travel time and energy dissipation minima for potential flows in heterogeneous geologic media

Travel time and energy dissipation minima for potential flows in heterogeneous geologic media