Permeability Parameters Research Articles

Influence of Buoyant Forces on Magnetohydrodynamics (MHD) Blood Flow with an Interaction of Thermal Radiation

In this study, the heat and mass transfer of the blood flow, particularly in a capillary tube having a porous lumen and permeable wall in the presence of external magnetic field are considered. The velocity, temperature and concentration of blood flow become unsteady due to the time dependence of the stretching velocity, surface temperature and surface concentration. The thermal and mass buoyancy effect on blood flow, heat transfer and mass transfer are taken into account in the presence of thermal radiation. This analysis is very much useful in the treatment of cardiovascular disorders. The equations governing the flow under some assumptions are complex in nature, but capable of presenting the realistic model of blood flow using the theory of boundary layer approximation and similarity transformation. First, the system of coupled partial differential equations (PDEs) is converted into a system of coupled ordinary differential equations (ODEs). Then the solutions are obtained by Runge-Kutta method of 4thorder with shooting technique. The effects of various parameters such as Hartman number, radiation parameter, unsteadiness parameter, permeable parameter, thermal buoyancy parameter, Prandtl number, mass buoyancy parameter, velocity slip parameter, thermal slip parameter, Schmidt number on velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number are depicted through graphs. Local Sherwood number enhances because of increase in Schmidt number. Moreover, some of the important results, which are discussed in the present study and have an impact on diseases like hyperthermia, stoke and moyamoya in human body.

A permeability evolution model of coal particle from the perspective of adsorption deformation

AbstractAs an important indicator, permeability can predict the gas drainage yield and prevent the mine gas disasters. We first reviewed our previous inversion method to investigate permeability coefficient of gas in coal particles; however, the relationship between permeability and adsorption pressure had not been summarized and explained theoretically. Here, a permeability evolution model including two crucial parameters of initial permeability and deformation coefficient was developed. The inversion gas permeability coefficients were converted into permeability, and then, the permeability of the same coal sample was fitted according to the evolution model. The results show that (i) the modeled results are matched reasonably well with the inversion permeability data, and thus, this model has been validated; and (ii) as volatile matter content increases, the initial permeability decreases exponentially, but the deformation coefficient basically grows in a linear trend. These two parameters are coupling to lead to a negative exponential decrease in permeability as gas pressure rises.

A novel approach for measuring plane anisotropic permeability through steady-state flow between two concentric cylinders

Anisotropy is a common feature for most of fibrous and porous media. This article reports a new method for measuring the 2D anisotropic permeability of a porous rock utilizing the measurements obtained from the steady-state flow between two concentric cylinders. The mathematical analysis of the experimental data is based on the general solution of the pressure equation derived for the steady-state flow equation for an anisotropic porous medium between two concentric cylinders. The general solution, incorporating the degree of anisotropy and the ratio between inner and outer cylinder radii, is presented in a dimensionless form. The solution shows that pressure distribution between the two cylinders is composed of an isotropic part plus a series representing the contribution of the anisotropy. The solution is validated through the comparison against numerically derived results and the analytical solution of two extreme cases; when the clearance between the two cylinders vanishes, and when the material is isotropic. The validation shows a perfect performance of the proposed solution even in the vicinity of the inner cylinder not like the approximate solutions existing in the literature. The validation also shows that the truncation of the series part has an impact on the results specially in the case of extreme anisotropy. Two experimental procedures 1) basic approach and 2) modified approach, utilizing the “pear” and “tent” charts derived from the general solution, demonstrate how to obtain the principle permeabilities and their directions. The applicability of the proposed experimental techniques is attained through the application of the modified approach over real experimental data from a holed core experiment to estimate anisotropic permeability parameters. The application of the proposed technique and the required modifications for measuring the anisotropy in tight cores are discussed. Also, the relation between the three-dimension anisotropy and the presented plane anisotropy is presented.

On the process of filtration of fractional viscoelastic liquid food

In the process of filtration, fluid impurities precipitate/accumulate; this results in an uneven inner wall of the filter, consequently leading to non-uniform suction/injection. The Riemannian–Liouville fractional derivative model is used to investigate viscoelastic incompressible liquid food flowing through a permeable plate and to generalize Fick’s law. Moreover, we consider steady-state mass balance during ultrafiltration on a plate surface, and a fractional-order concentration boundary condition is established, thereby rendering the problem real and complex. The governing equation is numerically solved using the finite difference algorithm. The effects of the fractional constitutive models, generalized Reynolds number, generalized Schmidt number, and permeability parameter on the velocity and concentration fields are compared. The results show that an increase in fractional-order α in the momentum equation leads to a decrease in the horizontal velocity. Anomalous diffusion described by the fractional derivative model weakens the mass transfer; therefore, the concentration decreases with increasing fractional derivative γ in the concentration equation.

Heat transfer and entropy generation analysis in a horizontal channel filled with a permeable medium in the presence of aligned magnetic field and temperature gradient heat source

The current investigation is concerned with heat transfer and entropy generation analysis in a horizontal channel brimming with porous medium in the existence of aligned magnetic field, viscous and joules dissipation and temperature gradient heat source. The boundary conditions are treated as constant values for velocity and temperature at lower and upper walls. An explicit solution of governing equations has been attained in closed system. The repercussions of pertinent parameters on the fluid velocity, temperature, entropy generation and Bejan number are conferred and scrutinized through graphs in detail. Additionally the expressions for shear stress and the rate of heat transfer coefficients at the channel walls are derived and results obtained are physically interpreted through tables. From the conquered results, it is addressed that Brinkman number Br enhances boundary layer thickness. Entropy generation increases with intensifying values of M, aligned angle ϕ, temperature gradient heat source parameter Q, characteristic temperature ration omega and permeability parameter K. The shear stress is same at both the lower and upper walls.

Simulation and analysis of dynamic wettability alteration and correlation of wettability-related parameters during smart water injection in a carbonate core

Low salinity/Smart water injection (LSWI) is a promising enhanced oil recovery (EOR) method, where manipulating the injected water compositions helps in recovery from oil reservoirs via alteration of the rock wettability towards a more water-wet state. In this paper, the experimental data of LSWI in a carbonate core sample have been simulated and matched. The experimental results of oil recovery by injection of four different waters were examined, and the relative permeability curves were adjusted using a dynamic wettability alteration approach. Moreover, results of drainage and imbibition tests used to approximate the corresponding capillary pressures. True effective mobility (TEM) functions were also derived to evaluate the two-phase flow characteristics of the systems. Relative permeability and capillary pressure parameters showed strong correspondence with the injected salinity, and correlations were proposed for estimating the unknown parameters in other similar studies with different salinities. The trend of wettability alteration by LSWI was investigated, and it was concluded that the wettability does not linearly change with salinity, but rather it is non-linearly correlated with the logarithm of the total injected salinity. Injection of seawater (SW) did not significantly change the wettability and flow efficiency of the system compared to formation water (FW). However, dilution of SW to the salinity of 5000 ppm seemed to be the critical threshold below which the effect of LSWI had become substantially more pronounced. The results of this study can be helpful in optimizing and upscaling similar smart water applications, predicting the wettability-related parameters and two-phase flow characteristics at different injected salinities, and also block-to-block modelling in which the effect of the capillary pressure in the fracture network is also considered. Additionally, the non-linear relationship of the wettability-related parameters with salinity is particularly considerable for modifying the common modelling approaches of wettability alteration by LSWI in commercial simulators.

Simulation of Groundwater Flow in Fractured-Karst Aquifer with a Coupled Model in Maling Reservoir, China

A coupled model has been developed to simulate groundwater flow in fractured karst systems according to the complex geological and karst hydrogeological conditions of the dam site, where a 3D mathematical model based on Boussinesq equation was used to describe the movement of groundwater flow in fractured medium, and a 1D conduit model for karst medium. The model was solved with the continuous hydraulic heads at the common boundaries. The hydraulic conductivities of karst medium were determined by geometrical parameters and flux of pipes. Furthermore, the permeability parameters for fractured medium were calibrated by the measured and calculated groundwater levels. The calibrated model was employed to predict the variation of groundwater flow field and leakage from the karst pipes and underground powerhouse during the reservoir operation. The simulated results showed that the groundwater level of the powerhouse had decreased by about 2–5 m. The water level of conveyance pipeline had risen by 10–20 m, and the water level on both banks had risen by 15–25 m. The leakage of karst conduits for impervious failure was larger than that for normal seepage control. In addition, the leakage of the powerhouse was estimated to be about 1000–3000 m3/d, and the seepage control of karst pipes had little influence on the leakage of underground powerhouse.

A study of non-isothermal permeable flow of nano-fluids in a stretchable rotating disk system

The rapid development of modern nanotechnology has brought about the importance of particles of nanometer-size (normally less than 100 nm) as compared to those of macro meter-size. Occurrences of heat transfer in flow of nanofluids are more prominent in industries and advanced technological processes. Transportation, atomic reactors, lubricating system and polymer processing are few of such processes. A non-isothermal permeable flow of nanofluids between dual stretching and rotating disks was examined. The governing nonlinear conservation equations were considered in cylindrical coordinate and Von Karman transformations were rendered into the system, the emerging boundary value problem was associated with a number of dimensionless parameters, such as, Prandtl number, upper and lower disk stretching parameters, permeability and relative rotation rate parameters. The Nano- fluid model was used to account for the effects of Brownian and Thermophoresis motion on the flow system. The resulting nonlinear system of equations is then solved using Newton’s Finite difference technique by MAPLE 18.0 software. The numerical solution obtained showed the effects of the associated physical parameters on the velocities, temperature, pressure and the concentration profiles presented graphically.

MHD Three-Dimensional Free Convective Flow with Periodic Permeability and Heat Transfer of a Second-Grade Fluid

The present study delivers the mathematical model and theoretical analysis of a three-dimensional flow in a free convection for an electrically conducting incompressible second-grade fluid through a very high porous medium circumscribed by an infinite vertical porous plate subject to a constant suction. A uniform magnetic field along the normal to the surface of plate is applied. Periodic permeability for the medium is assumed, while velocity of free stream is taken to be uniform. Analytic expressions are presented for velocity and temperature fields, pressure, and skin friction components by perturbation technique. The impacts on these physical quantities by the physical parameters existing in the model are discussed and envisioned graphically. It is interesting to note that elastic and permeability parameters are able to control the skin friction along the main flow direction, magnetic field to reduce the pressure, and Reynolds number to control the thermal boundary layer thickness. It is also noted that temperature distribution does not depend upon permeability parameter.

Dufour effect on MHD flow past an exponentially accelerated vertical plate through porous system with variable temperature and mass diffusion

The purpose of this study is to examine the effect of Dufour on the exponentially accelerated plate past MHD flow through porous media with varying temperatures and constant mass distribution. The considered fluid conducts electricity. The set of dimensionless area differential equations is solved by using the Laplace transformation technique and by finding the value of velocity, temperature and concentration profiles. The outcomes are found by graphs for various boundaries such as warm Grashof value, mass Grashof value, Prandtl value, permeability parameter, Schmidt value, Dufour value, time, magnetic flux tendency and acceleration parameter. The velocity profile decreases by increasing the values ​​of the magnetic parameter, radiation absorption, chemical reaction and thermal radiation. The temperature profile increases by increasing the values ​​of the thermal radiation and the Dufour number.

Evaluation of microvascular permeability of skeletal muscle and texture analysis based on DCE-MRI in alloxan-induced diabetic rabbits.

To estimate the microvascular permeability and perfusion of skeletal muscle by using quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and explore the feasibility of using texture analysis (TA) to evaluate subtle structural changes of diabetic muscles. Twenty-four rabbits were randomly divided into diabetic (n = 14) and control (n = 10) groups, and underwent axial DCE-MRI of the multifidus muscle (0, 4, 8, 12, and 16 weeks after alloxan injection). The pharmacokinetic model was used to calculate the permeability parameters; texture parameters were extracted from volume transfer constant (Ktrans) map. The two-sample t test/Mann-Whitney U test, repeated measures analysis of variance/Friedman test, and Pearson correlations were used for data analysis. In the diabetic group, Ktrans and rate constant (Kep) increased significantly at week 8 and then showed a decreasing trend. Extravascular extracellular space volume fraction (Ve) increased and plasma volume fraction (Vp) decreased significantly from the 8th week. Skewness began to decrease at the 4th week. Median Ktrans and entropy increased significantly, while inverse difference moment decreased from the 8th week. Energy decreased while contrast increased only at week 8. Muscle fibre cross-sectional area was negatively correlated with Ve. The capillary-to-fibre ratio was positively correlated with Vp (p < 0.05, all). Quantitative DCE-MRI can be used to evaluate microvascular permeability and perfusion in diabetic skeletal muscle at an early stage; TA based on Ktrans map can identify microarchitectural modifications in diabetic muscles. • Four quantitative parameters of DCE-MRI can be used to evaluate microvascular permeability and perfusion of skeletal muscle in diabetic models at early stages. • Texture analysis based on Ktrans map can identify subtle structural changes in diabetic muscles.

Identification of hydrogen permeability and thermal desorption parameters of vanadium-based membrane

The paper implements a two-stage “penetration + thermal desorption” experiment for the complex estimation of hydrogen permeability and thermal desorption parameters (sorption, dissolution, diffusion and desorption) of vanadium-based membrane. A gradual growth of the thermal desorption flux at high temperature is interpreted as a lowering of the potential surface barrier (primarily due to the loss of oxides). Indirect evidence of that is the stability of the critical temperature. Effectively, this entails a reduction of the desorption activation energy. The obtained effective values of the physicochemical parameters describe a series of experimental curves (at different initial sample temperatures, different molecular hydrogen input pressures, different heating rates at the TDS stage) and allow modeling numerically the penetration and thermal desorption across a wide range of conditions (including experimentally difficult ones) and estimating quantitatively the spectrum's reaction to variation of the limiting factors.

Increase adapalene delivery using chemical and herbal enhancers.

Acne is one of the skin diseases that include abnormalities in the production of sebum, changes in the microbial flora, abnormal keratinization, and inflammation. Adapalene is a good choice in the treatment of acne with fewer side effects and high effectiveness. However, the absorption of adapalene through human skin is low. We investigated the effect of several enhancers on the skin absorption of adapalene. For the preparation of a topical formulation, this drug needs proper skin absorption. Therefore, to increase the effect of chemical absorption of the Adapalene skin permeability, it should first be put on the skin in a touch of some absorption like Eucalyptus, Urea, Clove oil, propylene glycol, and oleic acid for 1 and 2hours and was then examined for the passing of the drug on the treated skin and for the effect of absorptions by calculating of the permeability parameters using DSC and FT-IR techniques. The results show that the enhancers used increased the permeability of the drug adapalene to water. Several mechanisms including lipid liquefaction, degradation of the fat structure, as well as irreversible denaturation of intracellular creatine caused by Eucalyptus, urea clove oil, PG, and oleic acid are the main mechanisms of drug penetration. Based on the results, it was found that among the enhancers studied, eucalyptus and urea had the highest and the lowest absorption effect in 2- and 1-hour pre-contact, respectively.

Injection and Extraction of Atomic Hydrogen on Cu–Pd- and Ag–Pd-Alloys in Alkaline Medium

The behavior of alloys of the Cu–Pd- and Ag–Pd-systems in the hydrogen evolution reaction in 0.1 M KOH aqueous solution is investigated. The role of copper and silver in the processes of the atomic hydrogen insertion and ionization is revealed. The mechanism of the hydrogen evolution reaction in aqueous alkaline solution on Cu,Pd- and Ag,Pd-alloys with the electronegative component content up to 60 at % is proposed. The limiting stage of the hydrogen evolution reaction on the palladium alloys in 0.1 M KOH is shown to be the atomic hydrogen ionization complicated by its diffusion in the solid phase. The parameters of hydrogen permeability for the systems under study are calculated. The maximum hydrogen permeability is achieved on the Ag80Pd alloy. Accordingly, alloys with higher palladium content, along with pure palladium, can be successfully used as effective materials for the atomic hydrogen purification and storage.

Research on the Effect of Uneven Proppant Settlement on Well Productivity in Stimulated Reservoir

The characteristics of proppant tarnsportation, settlement and distribution in fractures are of great significance to the effectiveness of complex fractures, as well to investigate the shale reservoir stimulation volume and productivity evaluation. This paper studies the effect of the uneven distribution of proppant sand banks on well productivity. A numerical model that comprehensively considers adsorption, desorption and stress sensitivity, and characterizes different settlement degree of proppant sand banks is established. The pressure distribution and productivity characteristics of fractured reservoir considering proppant non-uniform distribution are studied, by comparative analysis of different sand bank shapes, main fracture conductivity, reservoir matrix permeability and other sensitivity parameters. Meanwhile, the main controlling factor that affects the productivity of horizontal wells after the formation of sand banks are obtained. The results show that the proppant settlement greatly reduces the productivity. The effect of fracture conductivity on well production could ignore when the fracture conductivity is more than 4 μm2·cm in specific fractured reservoir. It is recommended to use small particle size proppant (100 mesh) to propped natural fractures or induce fractures. The higher the matrix permeability, the greater the impact of proppant settlement on well productivity. Beisdes, the measurement to prevent proppant settlement should be taken in high permeability zones. Considering the influence of proppant uneven settlement in complex fractures is of great significance for evaluating well productivity and guiding on-site fracturing operations.

CALCULATING THE PERMEABILITY PARAMETERS OF THE STAG-GERED ZONE BASED ON THE NONLINEAR FLOW SIMULATION OF THE HIGH-PRESSURE PACKER TEST

In the construction of high dam reservoir, it is necessary to determine the permeability parameters of the rock and soil near the engineering area under the condition of high water head, and high-pressure packer test is one of the most commonly used methods. Compared with other tests, the water head and seepage velocity are very high during the high-pressure packer test, and the nonlinear flow is prone to show up. In this case, the Darcy's law is no longer applicable. Therefore, a method for determining nonlinear parameters based on the high-pressure packer test is urgently needed. In this paper, a nonlinear flow mathematical model of the high-pressure packer test is established. By using the finite difference method, the numerical solution of the nonlinear flow mathematical model under the condition of step head is obtained, and the accuracy of the numerical solution is verified. On this basis, the influence of nonlinear parameters on water head h and flow velocity v is discussed. Combining with the in-situ high-pressure packer test at Baihetan Hydropower Station, the nonlinear parameters are calculated to further verify the reliability of the method. The results show that when the nonlinear parameter k and the radial distance r remain unchanged, the larger the nonlinear parameter β, the smaller the h and the v during the test. When β and r remain unchanged, the larger the nonlinear parameter k, the higher the h and the smaller v during the test. Furthermore, larger β and k will make the packer test reach a steady state faster. If the calculation is still carried out according to the Darcy equation, the water head in the permeable medium will be overestimated, and then the ability of the structural surface to resist seepage damage will be overestimated, which will eventually have a negative impact on the stability of the project. Non-linear movement of groundwater occurred during the field high-pressure packer test at Baihetan Hydropower Station, and the nonlinear parameters of the C2 staggered zone as follows: β=1.62 min ·m-1, k=9.60×10-3m ·min-1, this method has good applicability for determining the nonlinear parameters of the staggered zone on site.

Radiation-absorption, chemical reaction, Hall and ion slip impacts on magnetohydrodynamic free convective flow over semi-infinite moving absorbent surface

The investigation of radiation-absorption, chemical reaction, Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous, electrically conducting and heat generation/absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been premeditated. The plate is assumed to be moving with a constant velocity in the direction of fluid movement. A uniform transverse magnetic field is applied at right angles to the porous surface, which is absorbing the fluid with a suction velocity changing with time. The non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic functions. The graphical results of velocity, temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent parameters. It is found that the velocity profiles decreased with an increasing in Hartmann number, rotation parameter, the Schmidt number, heat source parameter, while it increased due to an increase in permeability parameter, radiation-absorption parameter, Hall and ion slip parameters. However, the temperature profile is an increasing function of radiation- absorption parameter, whereas an increase in chemical reaction parameter, the Schmidt number Sc or frequency of oscillations decrease the temperature profile on cooling. Also, it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.

Effect of preparation conditions on gas permeability parameters of porous SiC ceramics

The influence of binder content, firing temperature, SiC particle size, activated carbon content and activated carbon particle size on gas permeability parameters of porous SiC ceramics were investigated according to their pore structure performances and microstructure. The influencing degree of these preparing conditions on gas permeability parameters were also compared. The results showed that Darcian permeability parameter k1 and non-Darcian permeability parameter k2 increase with increasing of SiC particle size, activated carbon content and activated carbon particle size, but with decreasing of binder content and firing temperature. Binder content and activated carbon particle size have more significant effects on k1 than other three preparing conditions which their influencing degree in descending order are activated carbon content, SiC particle size and firing temperature. The influencing degree of preparing conditions on k2 and k1/k2 are ambiguous, but it is clear that SiC particle size have largest influence on k2 and k1/k2.

Behavior of Conical Porous Hybrid Journal Bearing with Pseudoplastic Lubricant

In recent years, porous bearings have been increasingly used in various industrial applications because they are less noisy, have good precision, and are relatively maintenance free. In this article, the numerical analysis of a conical porous hybrid journal bearing system (CPHJBS) has been carried out. The interactive effects of permeability parameter, semi cone angle, and pseudoplastic (shear thinning) lubricant behavior on the performance of CPHJBS have been theoretically investigated. The governing Reynolds equation for a non-Newtonian lubricant in the bearing clearance space of CPHJBS is solved using a finite element model. Findings of this study indicate that the CPHJBS operating with a pseudoplastic lubricant offers a higher value of stability threshold speed margin for the lower value of semi cone angle and lower value of permeability parameter

A Machine Learning Approach to Predicting the Heat Convection and Thermodynamics of an External Flow of Hybrid Nanofluid

Abstract This study numerically investigates heat convection and entropy generation in a hybrid nanofluid (Al2O3–Cu–water) flowing around a cylinder embedded in porous media. An artificial neural network is used for predictive analysis, in which numerical data are generated to train an intelligence algorithm and to optimize the prediction errors. Results show that the heat transfer of the system increases when the Reynolds number, permeability parameter, or volume fraction of nanoparticles increases. However, the functional forms of these dependencies are complex. In particular, increasing the nanoparticle concentration is found to have a nonmonotonic effect on entropy generation. The simulated and predicted data are subjected to particle swarm optimization to produce correlations for the shear stress and Nusselt number. This study demonstrates the capability of artificial intelligence algorithms in predicting the thermohydraulics and thermodynamics of thermal and solutal systems.