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A pressure-based coupled heat and mass transfer model was used to simulate temperature and soil suction in a drying process within a clay soil column. Closed form functions were used for all parameters needed in the governing equations. Model predictions were compared with experimental data using the mean relative percentage deviation method. Thermocouples and mini-gypsum blocks were used to monitor the data collected hourly at different depths of the soil column. The model showed very high sensitivity to the proposed hydraulic conductivity function, while lower sensitivity was found for the proposed thermal conductivity function. This result highlights the importance of a proper hydraulic conductivity estimate while a rough estimate for thermal conductivity would have no significant adverse effect on the predicted values.

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In order to investigate the effect of various parameters on the adsorption chiller performance, the adsorbent bed should be modeled with appropriate governing equations and assumptions. In order to study the adsorption chiller numerically, the governing equations should be modeled in four domains of thermal fluid, metal tube, fins and adsorbent bed simultaneously. One of the assumptions, which greatly influenced the modeling complexity and computation cost is the uniform pressure approach for the bed. For some of modeling conditions the pressure of the bed should be calculated and the inter particle resistance cannot be neglected. In this study with comparing the governing equations of uniform pressure and non-uniform pressure approach, a dimensionless number is introduced and a limiting value is determined with the help of numerical results such as specific cooling power. This parameter can be employed to decide about the appropriate bed pressure assumption prior to start the modeling process.

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In this paper the problem of coupled radiation and natural convection is investigated in a square porous cavity using local thermal non-equilibrium model. The radiative transfer equation (RTE) is solved by the discrete ordinates method (DOM) and the energy and momentum equations are solved using finite element method. The results of the present study are compared with that of the other investigations which have used another method to solve radiative transfer equation. Effective parameters on heat transfer and fluid flow characteristics such as Planck number, inter-phase heat transfer coefficient and scattering albedo are studied and the results are presented in the group of dimensionless parameters. The results indicate that the solving method of the radiative transfer equation would have significant effect on the fluid flow and heat transfer characteristic. In the case of low optically thick media, discrete ordinates method (DOM) is more precise than the other methods which used in other literature.

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Two-phase flow modeling has been the subject of many investigations. However, fewer studies are corresponded for two-phase flow within a porous medium, because of additional complications. In this paper, two-phase flow with the density and viscosity ratio of 1, within a porous medium is simulated by Shan and Chen model. Due to inherent limitations and weaknesses of this approach in an independent control of surface tension, investigation of parameters such as Reynolds number, Froude and Weber is not applicable. However, porous medium parameters such as Darcy number and contact angle could be studied by changing the porous medium and contact angle. Competition between opposing forces against the drop and the capillary effect because of increasing the number of particles in the porous media is described using the Darcy number. Also the effect of the contact angle between liquid-gas phases and the solid surface is evaluated on the droplet penetration inside the porous medium.

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A two dimensional numerical study is presented for steady state performance analysis of a catalytic radiant counter-diffusive burner. In these burners, the gaseous fuel enters from the rear of the burner and passes through the insulation and catalyst layers. The oxygen enters the catalyst layer from the burner surface and opposite to the fuel path. The reaction takes place over the catalyst layer. In this paper, the momentum, energy and species conservation equations in porous and non-porous media are solved using the finite element method in the COMSOL software. The simulations are based on proposed corrections on boundary conditions and combustion rate of methane equation. The simulation results compared with experimental measurements published in the literature for the same geometry and conditions which shows a considerable (10%) improvements. It is shown that diffusion of oxygen through the pad limits the catalytic combustion and controls the fuel conversion in the burner.

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In this paper, natural convection of Cu-Water nanofluid inside an enclosure which is partially filled with porous media, with internal heat generation has been studied numerically. Cu-water nanofluid was used where Maxwell and Brinkmen models determine its properties. Due to the low velocity of nanofluid, Darcy-Brinkman equation used for the modeling of porous media. In order to gain the maximum energy from the temperature dependent heat source, different parameters such as Rayleigh number, volume fraction of nanoparticles, porosity of porous matrix and heat conduction ratio has been investigated. The results show that increasing the volume fraction of nanofluid increases Nusselt number at all porosities and Nusselt will further increases at lower porosities. Changes of thermal conductivity ratio were effective only at low porosities and causes to fast conduction of generated heat and two-fold increase in Nusselt number. Moreover the porosity changes at different thermal conductivity ratio Cause to minimum Nusselt at the porosity of 0.4 to 0.6. Increasing Rayleigh number will lead to nanofluid penetration increase into the porous matrix and with further matrix cooling more increase in Nusselt number in all porosity ranges will be achieved.

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Although,the physical activity in the cold condition causes the body temperature to rise,it can be a significant factor in the occurrence of thermal discomfort due to increase in the perspiration rate and water gathering in the fabric.Moreover,the accumulated water at the inner side of the clothing can cause a difficulty in the skin respiration. So, the amount of accumulated water and interior surface wetness are important indices for evaluating the suitability of clothing for winter activity. The aim of this study is to determine the amount of accumulated water in various arrangements of multi-layer clothing assemblies containing of three bathing layers of Polyester and Viscose in a very cold environment (with -20C temperature).For this reason,the clothing has been modeled as a porous media with multi-phases and multi-species flow by considering the sorption and condensation phenomena.Also,the implicit finite volume numerical method has been used for discretizing and solving the governing equations.The results show that locating the non-absorbing polyester fabric at the layer adjacent to the skin causes the wetness to decrease at this region. Also, locating the polyester at the outer layer can help to maintain the clothing temperature at the proper conditions.Also,the results indicate that using the viscose fabric as the middle layer leads to decrease in the water content value at the center of clothing. Therefore, the “polyester-viscose-polyester” arrangement can properly remove the perspiratory moisture from the skin to environment, with the minimum of inner water content index (0.02) and maximum inner surface temperature(33C) and average clothing temperature(16.1C).

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In this study forced convection heat transfer in a pebble bed cylindrical channel with internal heat generation was investigated experimentally. Dry air has been used as working fluid in heated spheres cooling process. Internal heating was generated uniformly, by electromagnetic induction heating method in a metallic spheres which have been used in test section. Spheres are made of stainless steel and their diameter is in the range of 5.5-7.5 mm. Present study was performed at steady state and turbulence flow regime, with Re number in the range of 4500-9500. Different parameters resulted by variation of spheres diameter, flow velocity and generated heat on forced convection heat transfer was studied. According to thermal and hydrodynamics studies, it can be said as Re number increases, heat transfer coefficient will increase. Also heat transfer coefficient has been increased by spheres diameter decrement. The generated heat has a little influence on heat transfer coefficient. The effect of pressure variations on forced convection heat transfer can be neglected. Porous channel has greater friction factor in comparison with an empty channel. The friction factor in empty channel is always less than 1 but for porous channel this parameter is in the range of 10-25.

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The viscous fingering instability of miscible non-Newtonian flow displacements in anisotropic porous media is studied. This instability was studied in a rectilinear Hele-Shaw cell and the shear-thinning character of the fluids has been modeled using the Carreau-Yasuda constitutive equation. In particular, the role of anisotropic properties of porous media including permeability and dispersion and also rheological parameters of non-Newtonian fluid is investigated through nonlinear simulation. In non-linear simulations, a spectral method based on the Hartley transforms are conducted and allowed to compare several non-linear finger interactions were observed in simulation. In this paper, three types of displacement are considered. In the first one, the displacing fluid and the displaced one are Newtonian and in the next two types of displacement, one of the displacing fluids or the displaced one is non-Newtonian. The evaluation of mixing length, sweep efficiency and transversely average concentration are examined for two different types of displacement where the displacing or the displaced phase were shear-thinning fluids and also for different anisotropic scenarios. The results indicate that in three types of displacement, the flow is more stable by increasing the anisotropic permeability ratio and also is more unstable by increasing the anisotropic dispersion ratio. Moreover, it’s concluded that in the case of the non-Newtonian fluid displaced the Newtonian fluid, by increasing the Deborah number and the power-law index, the more stable flow is obtained, while in the case of the Newtonian displaced the non-Newtonian one, the more unstable flow is obtained.

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In this paper two automated and robust algorithms for generation of unstructured grids suitable for miltiscale finite volume method in oil reservoirs is presented. The multiscale finite volume method is an efficient numerical method for flow simulation in porous media. The multiscale finite volume method has been extensively studied on structured grids. In this research multiscale finite volume method is extended to unstructured grids. Development of the MSFV method to unstructured grids provides advantages of flexibility and compatibility with geological structures. In this method calculations are carried out on three grids, fine grid, primal coarse grid and dual coarse grid. One of the main challenges to extend the multiscale finite volume method to unstructured grids is to generate primal and dual coarse grids. In this paper an algorithm for partitioning of unstructured grid and generating primal coarse grid is proposed. Also a new algorithm for generating dual coarse grid is presented. Finally, the proposed algorithms for generating multiscale unstructured grids are employed for flow simulations in porous media. Numerical results show that the multiscale finite volume method with generated multiscale unstructured grids of this research can accurately predict the fine scale solution.

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Simulation and analysis of two phase flow that crosses over tube bundles is crucial in safety analysis and design of kettle reboilers and steam generators. The geometry complexity of the tube bundle flow field increases the difficulty of the conventional numerical analysis. One of the methods to reduce the numerical calculations cost, is to use the porous media theory instead of the complete tube bundle modeling. Drag and tube bundle resistance force equations have been used in the porous media analysis. Based on available experimental results, two tube bundle arrangements have been considered. Due to existence of symmetric geometry and uniform energy source over the tube bundle, the two dimensional symmetric models has been used as well. It was observed that the predicted pressure drop in this research has acceptable adaptation with the experimental results. Meanwhile, by considering different outlet boundary conditions, calculated void fraction is compared to the experimental results and showed better accuracy than similar CFD research. It was observed that the enhancement of the tube bundle thermal power increases the void fraction in the heating area of the reboiler.

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In the present study, the pressure equation associated with two-phase, incompressible and immiscible flow in porous media is solved by the multi-scale finite volume method (MsFV) for 2D problems. The MsFV method along with its main source of errors is mathematically and physically described. Associated with the computational grids used in the MsFV method, a set of two-scale isotropic permeability domains is designed. These permeability domains are produced to show how and where the errors are initiated in the pressure domain of the MsFV method. For each permeability domain, the pressure and velocity solutions obtained by the multi-scale method are compared with those of the standard finite volume method (as the reference solutions). The numerical results indicate that the MsFV method is sensitive to the fine cells with low permeability data located at the faces and corners of the dual grid blocks. The most errors is observed when the corners of the dual blocks are located on fine cells with low permeability value. In addition. By introducing the adjusted boundary condition, the effects of the permeability averaging for the edges and corners of the dual blocks on the MsFV errors are also investigated.

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Steam generators as an interface between first and second loop of light water nuclear power plants is very important in design and safety analysis. Thermo hydraulic analysis can affect the design and operation of a horizontal steam generator using prediction of vapor distribution. In this kind of thermo hydraulic analysis, simulation and study of the tube bundles is crucial in design and safety study of the steam generator two phase flow field. In this research, due to high complexity of the numerical simulation, the tube bundles have been assumed as the porous media. Two phase flow field correlations such as interfacial drag force and tube bundle resistance force have obtained by the equations that have been reported in the similar computational fluid dynamic researches. The heat transfer from primary side fluid to the secondary is calculated three-dimensionally each iteration and is supplied as a heat source on the secondary flow field calculation. Besides porous media flow field validation, decrease of computational domain has been studied using appropriate boundary conditions. It was observed that the computed void fraction compared to the experimental results show better accuracy than similar computational fluid dynamic investigations

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In this paper, the non-Newtonian immiscible two-phase polymer flow in a petroleum reservoir has been investigated numerically. The fluid flow in a porous medium is simulated as a compressible flow. The Carreau-Yasuda constitutive equation is employed as the model of non-Newtonian fluid. The IMPES method is used for numerical simulation, in which the pressure equation is discretized and solved by an implicit approach and the saturation equation is solved by an explicit method. Results reveal that zero-shear rate viscosity has a high impact on the sweep efficiency of the reservoir and also controls the channeling and viscous fingering effects. In addition increasing the viscosity of non-Newtonian fluid improves cumulative oil production and diminishes the viscous fingering phenomenon caused by injected fluid. The relaxation time of Carreau-Yasuda fluid, which is the elastic characteristic of the non-Newtonian fluid, for low permeability values cannot influence flow characteristics inside the reservoir, however for higher permeability values its effect becomes more sensible. Increasing the injection rates leads to the increase of fluid production, while the injection rate has an optimum range to reach the optimum oil production. In addition, the effect of variation of the injected fluid properties on the polymer breakthrough time has been investigated and results presented.

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In the present study, the incompressible flow through highly heterogeneous porous media is modeled by the Multi-resolution Multi-scale Finite Volume (MrMsFV) method. In order to focus on the effects of the absolute permeability structure on the accuracy and performance of the MrMsFV method, the single phase flow is considered and the effects of the gravity and variation of fluid viscosity and density are ignored. The accuracy of the MrMsFV method is examined by comparing its numerical results with those of the standard finite volume method. These permeability fields are extracted from the tenth comparative study problem of the society of petroleum engineering. For the permeability fields in which the permeability varies smoothly, it is shown that the MrMsFV method produces acceptable results. On the other hand, the numerical results along with mathematical analyses show that the MrMsFV method may produce pressure fields with unphysical peaks for channelized permeability fields. In these cases sufficient conditions for the monotonicity and boundedness of the solution are violated. In fact, the coarse scale transmissibilities may be computed in such a way that the coefficient matrix of the coarse scale pressure equation not to be a so-called M-matrix.

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Nowadays the use of Drug Eluting Stents (DESs) is considered as a successful method for the treatment of coronary artery blockage. In order to study the impact of the presence of topcoat on heparin-eluting stents efficacy, two designs (with and without drug free topcoat) have been compared to each other. Moreover, here the importance of the plasma flow as a controversial topic among researchers has been studied. In order to closer to reality heart working, plasma flow is considered as a pulsatile fashion. Also, the injury of the coronary artery penetrated to a depth of media layer during angioplasty. Volume-averaged porous media equations which describe the drug release dynamics are employed and solved numerically by Finite Volume Method (FVM). Results put the amount of strut penetration in the forefront of importance. Local drug pharmacokinetics experiences significant changes by strut passing through endothelium, intima and Internal Elastic Lamina (IEL) and being contiguous with media layer. Although the plasma flow decreases/increases the amount of concentration level and subsequently decreases/increases the amount of drug mass in media/adventitia layer, but the results show that these effects are not significant. Among other findings, it is notable that the presence of topcoat has a negligible effect on the release characteristics.

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In-stent restenosis is one of the important inefficient reasons about Drug Eluting Stents (DESs). Awareness of how polymer coated drug distributes by these devices provides valuable informations about its efficacy. Porous media theory has been employed in the modeling of drug polymer and the injured arterial wall composed of media and adventitia. The stabished coupled PDEs describing local pharmacokinets of heparin has been solved numerically by finite volume method. Two approaches, single phase and two phases models, has been chosen for coating and the effect of local mass non-equilibrium dynamics in the coating on drug distribution has been evaluated by allocating three magnitude for solid-liquid transfer time characteristic. Moreover, the effect of lost drug by vasavasorum and microcapilaries has been considered as well as cell metabolism. The results show a significant change in drug concentration distribution in the presence of phase change happening. Reducing in solid-liquid transfer time characteristic is associated with drastic reducing in both drug egression from polymer and wash out from adventitia and has a pleasant effect. Also, consumtion of drug declines concentration level in the wall dramatically, specially in adventitia.

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In this paper, the viscous fingering instability in miscible Newtonian fluid displacements is studied experimentally. Studying the results of this instability have widely application in oil extraction from ground bed oil reservoirs to the ground surface. In order to be more actualized results, a porous media with transparent walls and compact structure of spherical glass beads is constructed, that have close permeability to ground bed. The main purpose of this study is to investigate the effects of viscosity ratio, flow rate and Blake dimensionless number on the quality of growth and the shape of the fingers, also their effect on important physical parameters including the mixing length, sweep efficiency and noise growth to base state. The results showed that with increasing the viscosity ratio, instability and number of finger branches increases and more tiny fingers are formed. Also, increasing the viscosity ratio increases the mixing length and decreases the sweep efficiency. Likewise, with increasing the flow rate, it was observed that the number of wide fingers Increased and fingertips tend to spread. Furthermore, by studying the results it was found that increasing the flow rate, increases the sweep efficiency, but have No tangible effect on the mixing length. Also, the results show that increasing the Blake decreases the mixing length and increases the sweep efficiency.

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Peristaltic phenomenon is widely used for biologically tissues such as the digestive and excretion of urine systems. Fingered and roller pumps, hoses and internal pumps, pumps for waste management in the nuclear industry are also working on the wavy walls rules. Hence, in this paper, the magnetic hydrodynamic flow of nanofluids inside a curved porous channel, with peristaltic walls and within the internal heat source has been studied. In the present study, the flow is incompressible and the governing equations, including flow, heat and mass transfer are obtained by using an assumption of long wavelength. For solving the equations, the central finite difference approximation algorithm and Keller-box method are utilized. Heat transfer is reduced due to the presence of a magnetic field. Also, increasing the power of the heat source and the Darcy number reduces the heat transfer. Increasing porosity in the environment increases the heat transfer. Increasing the power of the heat source is accompanied by a reduction in velocity in the central line of the channel in the corrugated mode.
In this paper, by using the numerical solution results, the effect of various parameters such as source term, Darcy number and porosity on the velocity, distribution of temperature, the function of the magnetic force, increase the pressure on the wavelength, Nusselt number and also the flow trapping phenomenon has been studied.

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In current research, surface reaction phenomena in several packed bed reactors have been considered. Flow field through several fractal Sierpinski carpet porous media have been simulated by LBM. The endothermic Isopropanol dehydrogenization reaction has been considered as basic reaction mechanism and two major parameters of non-homogeneity and specific area in catalytic surface reaction have been investigated. To validate our numerical method, the obtained results have been compared to a recent benchmark study and adopted very well. Also, in both cases the porosity factor retained constant (ε=0.79). The results shown that, by three times increase in specific area, the reactant conversion rate is increased significantly (approximately one order of magnitude), and the pressure drop increased (nearly 5 times), too. Also, to consider non-homogeneity arrangement, the particle arrangements from small to large and large to small have been considered. In both, the pressure drop is approximately the same. At low Re, reactant conversion of both arrangement are the same but by increasing of Re, the packed bed reactor with large to small arrangement has a little more reactant conversion.