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Zeitschriftenartikel zum Thema „Porous jump“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 14. Februar 2022

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1

Avramenko, A. A., N. P. Dmitrenko, Yu Yu Kovetska und E. A. Kondratieva. „FEATURES OF HEAT TRANSFER IN A FLAT POROUS MICROCHANNEL“. Thermophysics and Thermal Power Engineering 42, Nr. 1 (12.04.2020): 12–18. http://dx.doi.org/10.31472/ttpe.1.2020.1.

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A steady heat transfer process of mixed convection in a flat vertical porous microchannel is considered. The results of simulation showed that Knudsen number effects are more significant in the neighborhood of the wall where growth of Knudsen numbers is accompanied with the velocity and temperature jumps on wall. With increasing parameter of porosity M (decreasing permeability), the flow velocity decreases and the velocity jump decrease as well. For all combinations of the criteria Ra, Kn and M increasing Knudsen number reduces heat transfer intensity. This can be attributed to increasing temperature jump on wall which causes deterioration of thermal interaction between the fluid and the wall. For low Rayleigh numbers increasing parameter M leads to increasing heat transfer since the temperature jump decrease on walls. For large Rayleigh numbers the trend becomes reversed, since for larger parameters M, the near-wall velocity decreases. For low Rayleigh numbers increasing the Knudsen number leads to decreasing hydraulic resistance coefficient, but with increasing parameter M leads to increasing this coefficient. At high Ra numbers increasing Knudsen number leads to growth of hydraulic resistance, which is due to increasing velocity gradient on the wall.

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2

Li, Hong Hai, und Yang Yang Cheng. „Effect of Porous-Jump Model Parameters on Membrane Flux Prediction“. Advanced Materials Research 734-737 (August 2013): 2210–13. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.2210.

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A three-dimensional computational fluid dynamics (CFD) simulation was performed to study the velocity distribution on membrane surface in membrane separation process, and the effect of face permeability, porous medium thickness, and pressure-jump coefficient of porous-jump model on membrane flux. The study shows that all the three factors have important impact on membrane flux. Membrane flux increases linearly with the increase of face permeability. When the membrane thickness is between 0.04~0.1mm, the membrane flux decreases with the increase of membrane thickness. The membrane flux decreases with the increase of pressure-jump coefficient. So that there must be a complex relationship between membrane flux and face permeability, porous medium thickness, and pressure-jump coefficient.

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3

Chen, Ming-Da, und Wang-Long Li. „Creeping Flow Relative to a Porous Spherical Shell“. Journal of Mechanics 16, Nr. 3 (September 2000): 137–43. http://dx.doi.org/10.1017/s1727719100001799.

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ABSTRACTIn this study, the problem of creeping flow relative to an isolated porous spherical shell has been examined. The Brinkman-extended Darcy equations and the Stokes' equations are utilized to model the flow in the porous region (shell region) and free fluid region (inside the core and outside the shell), respectively. The stress jump boundary conditions at the porous media/free fluid interfaces are included and the exact solution has been found. The drag experienced by the porous shell has been discussed for various jump parameters and shell thickness.

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4

Qiu, Li, Xiao-Dong Chen, Rui Wang und De-Peng Wang. „Macro fluid analysis of laminated fabric permeability“. Thermal Science 20, Nr. 3 (2016): 835–38. http://dx.doi.org/10.2298/tsci1603835q.

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A porous jump model is put forward to predict the breathability of laminated fabrics by utilizing fluent software. To simplify the parameter setting process, the methods of determining the parameters of jump porous model by means of fabric layers are studied. Also, effects of single/multi-layer fabrics and thickness on breathability are analyzed, indicating that fabric breathability reduces with the increase of layers. Multi-layer fabric is simplified into a single layer, and the fabric permeability is calculated by proportion. Moreover, the change curve of fabric layer and face permeability, as well as the equation between the fabric layer and the face permeability are obtained. Then, face permeability and pressure-jump coefficient parameters setting of porous jump model could be integrated into single parameter (i. e. fabric layers), which simplifies the fluent operation process and realizes the prediction of laminated fabric permeability.

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5

Liu, Fang, und Bao Ming Chen. „Natural Convection in a Cavity Partially Filled with a Vertical Porous Medium“. Advanced Materials Research 321 (August 2011): 15–18. http://dx.doi.org/10.4028/www.scientific.net/amr.321.15.

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The shear stress jump boundary condition that must be imposed at an interface between a porous medium and a free fluid in an enclosure is investigated. Two-domain approach is founded and finite element method is used to solve the problem. Three stress jump coefficients 0, 1, -1 are analyzed for different Rayleigh number, permeability and thickness of porous layer. Variation of Maximum stream function and Nusselt number show stronger convection and heat transfer when the stress jump coefficient is positive. There is little distinctive in flow and heat transfer when the value of coefficient is equal to 0 and -1.

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6

Zhou, Guo Li, und Zhen Ting Hou. „Stochastic generalized porous media equations with Lévy jump“. Acta Mathematica Sinica, English Series 27, Nr. 9 (15.08.2011): 1671–96. http://dx.doi.org/10.1007/s10114-011-9194-8.

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7

Zakirov, Timur R., und Maxim G. Khramchenkov. „Pore-scale investigation of the displacement fluid mechanics during two-phase flows in natural porous media under the dominance of capillary forces“. Georesursy 22, Nr. 1 (30.03.2020): 4–12. http://dx.doi.org/10.18599/grs.2020.1.4-12.

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This paper presents the results of numerical simulations of two-phase flows in porous media under capillary forces dominance. For modeling of immiscible two-phase flow, the lattice Boltzmann equations with multi relaxation time operator were applied, and the interface phenomena was described with the color-gradient method. The objective of study is to establish direct links between quantitative characteristics of the flow and invasion events, using high temporal resolution when detecting simulation results. This is one of the few works where Haines jumps (rapid invasion event which occurs at meniscus displacing from narrow pore throat to its wide body) are considered in three-dimensional natural pore space, but the focus is also on the displacement mechanics after jumps. It was revealed the sequence of pore scale events which can be considered as a period of drainage process: rapid invasion event during Haines jump; finish of jump and continuation of uniform invasion in current pore; switching of mobile interfaces and displacement in new region. The detected interface change, along with Haines jump, is another distinctive feature of the capillary forces action. The change of the mobile interfaces is manifested in step-like behavior of the front movement. It was obtained that statistical distributions of pressure drops during Haines jumps obey lognormal law. When investigating the flow rate and surface tension effect on the pressure drop statistics it was revealed that these parameters practically don’t affect on the statistical distribution and influence only on the magnitude of pressure drops and the number of individual Haines jumps.

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8

Li, Wang-Long. „Derivation of Modified Reynolds Equation—A Porous Media Model“. Journal of Tribology 121, Nr. 4 (01.10.1999): 823–29. http://dx.doi.org/10.1115/1.2834141.

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In this study, a porous media model is developed which can be applied to thin film lubrication problems. The microstructure of bearing surfaces is modeled as porous layers attached to the impermeable substrate. The Brinkman-extended Darcy equations and Stokes’ equations are utilized to model the flow in the porous region and fluid film region, respectively. The stress jump boundary condition at the porous media/fluid film interface and effects of viscous shear are included in deriving the modified Reynolds equation. The present model can correct and modify a previous study based on the Darcy model with slip-fiow effects or another based on the Brinkman-extended Darcy model with stress continuity at the porous media/fluid film interface. In the results, the effects of material properties: viscosity ratio (αi2), thickness of porous layer (Δi), permeability (Ki), stress jump parameter (βi), on the velocity distributions, and performance of one-dimensional converging wedge problems are discussed.

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9

Angot, Philippe. „Well-posed Stokes/Brinkman and Stokes/Darcy coupling revisited with new jump interface conditions“. ESAIM: Mathematical Modelling and Numerical Analysis 52, Nr. 5 (September 2018): 1875–911. http://dx.doi.org/10.1051/m2an/2017060.

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The global well-posedness in time is proved, with no restriction on the size of the data, for the Stokes/Brinkman and Stokes/Darcy coupled flow problems with new jump interface conditions recently derived by Angot et al. [Phys. Rev. E 95 (2017) 063302-1–063302-16] using asymptotic modelling and shown to be physically relevant. These original conditions include jumps of both stress and tangential velocity vectors at the fluid–porous interface. They can be viewed as generalizations for the multi-dimensional flow of Beavers and Joseph’s jump condition of tangential velocity and Ochoa-Tapia and Whitaker’s jump condition of shear stress. Therefore, they are different from those most commonly used in the literature. The case of Saffman’s approximation is also studied, but with a force balance for the cross-flow including the Darcy drag and inducing a law of pressure jump different from the usual one. The proof of these results follows the general framework briefly introduced by Angot [C. R. Math. Acad. Sci. Paris, Ser. I 348 (2010) 697–702; Appl. Math. Lett. 24 (2011) 803–810.] for the steady flow.

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10

Zhanabaev, Z. Zh. „WIDTH OF ENERGY BAND GAP OF NANOPOROUS SEMICONDUCTOR FILMS“. Eurasian Physical Technical Journal 17, Nr. 2 (24.12.2020): 39–44. http://dx.doi.org/10.31489/2020no2/39-44.

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The aim of this work is to experimentally clarify the reasons for the appearance of jumps in the current and memory of semiconductor nanoporous structures.Porous nanostructures were obtained by electrochemical etching. The current-voltage characteristics of the samples were measured for porous silicon and on thin films of a chalcogenide glassy semiconductor. The existence of jump-like switching and current hysteresis in porous silicon nanofilms under laser illumination is shown experimentally.A connection between the switching voltage values and the dependence of the band gap on the porosity of nanofilms is found. These results make it possible to construct a theory of current switching and its hysteresis based on the concepts of the theory of second-order phase transitions.

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11

Yin, Chenguang, Liancun Zheng, Chaoli Zhang und Xinxin Zhang. „Flow and Heat Transfer of Nanofluids Over a Rotating Porous Disk with Velocity Slip and Temperature Jump“. Zeitschrift für Naturforschung A 70, Nr. 5 (01.05.2015): 351–58. http://dx.doi.org/10.1515/zna-2015-0031.

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AbstractIn this article, we discuss the flow and heat transfer of nanofluids over a rotating porous disk with velocity slip and temperature jump. Three types of nanoparticles – Cu, Al2O3, and CuO – are considered with water as the base fluid. The nonlinear governing equations are reduced into ordinary differential equations by Von Karman transformations and solved using homotopy analysis method (HAM), which is verified in good agreement with numerical ones. The effects of involved parameters such as porous parameter, velocity slip, temperature jump, as well as the types of nanofluids on velocity and temperature fields are presented graphically and analysed.

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12

Ayub, Nurafizalwani, Ramli Omar, Mohamad Deraman, Ibrahim Abutalib, Zalita Zainuddin und Atiqah Abdul Aziz. „Characteristics of Porous Sb-Doped Barium Titanate Ceramics Fabricated by Adding Graphite“. Advanced Materials Research 1107 (Juni 2015): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.9.

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Porous Sb-doped barium titanate (Sb-BaTiO3) ceramics were fabricated by adding various amounts of graphite powders. The density, structure, microstructure, porosity and electrical resistivity of the porous Sb-BaTiO3 ceramics produced without and with graphite were investigated. All the sintered ceramics showed a tetragonal perovskite structure, irrespective of the amount of graphite added. The porosity of the ceramics increased and the grain size decreased with increasing graphite addition which mainly due to the exothermic reactions of the graphite and oxygen molecules in the ceramics. The prepared porous Sb-BaTiO3 ceramics exhibit PTCR behavior where the PTCR jump of the ceramics with graphite was about 103 which is higher than that of the ceramics without graphite. The increasing in the PTCR jump with increasing graphite addition was attributed mainly due to the increase in the electrical barrier height of grain boundaries and the porosity. It was found that the graphite is an effective pore forming agent for fabricating porous BaTiO3-based ceramics.

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13

SRINIVASACHARYA, D., und M. KRISHNA PRASAD. „CREEPING FLOW PAST A POROUS APPROXIMATELY SPHERICAL SHELL: STRESS JUMP BOUNDARY CONDITION“. ANZIAM Journal 52, Nr. 3 (Januar 2011): 289–300. http://dx.doi.org/10.1017/s144618111100071x.

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AbstractThe creeping flow of an incompressible viscous liquid past a porous approximately spherical shell is considered. The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier–Stokes equations. The flow within the porous annular region of the shell is governed by Brinkman’s model. The boundary conditions used at the interface are continuity of the velocity, continuity of the pressure and Ochoa-Tapia and Whitaker’s stress jump condition. An exact solution for the problem and an expression for the drag on the porous approximately spherical shell are obtained. The drag is evaluated numerically for several values of the parameters governing the flow.

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14

Guo, Bo-ling, und Guo-li Zhou. „Exponential stability of stochastic generalized porous media equations with jump“. Applied Mathematics and Mechanics 35, Nr. 8 (29.06.2014): 1067–78. http://dx.doi.org/10.1007/s10483-014-1845-7.

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15

Avramenko, A. A., M. M. Kovetskaya, Yu Yu Kovetska und T. V. Sorokina. „HEAT TRANSFER DURING HEAT CARRIER FLOW IN A VERTICAL POROUS MICROCHANNEL“. Thermophysics and Thermal Power Engineering 42, Nr. 1 (12.04.2020): 27–34. http://dx.doi.org/10.31472/ttpe.1.2020.3.

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Heat transfer with a steady flow of coolant in a vertical microchannel filled with a porous medium is considered. The influence of porosity, the slippage effect on the wall, and the Rayleigh number on heat transfer are analyzed. The simulation results showed that with an increasing of the porosity parameter M (decrease permeability), the flow velocity decreases, the velocity jump on the wall also decreases, and the velocity profile becomes more filled. With an increase in the Rayleigh number, the relative flow velocity decreases, the shape of the velocity profile changes, it becomes M-shaped. At high Rayleigh numbers, the effect of free convection becomes predominant, and the shift of the maximum velocity to the channel wall is associated with a decrease in the density of the medium near the wall. With an increase in the Rayleigh number and the parameter M, the temperature jump on the wall decreases, local temperature values tend to the wall temperature values, the shape of the temperature profile aligns. An increase in the Knudsen number decreases the heat transfer rate. This is due to an increase in the temperature jump on the wall, which causes degradation in the conditions of thermal interaction between the liquid and the wall.The dynamics of change of the relative Nusselt number with increasing Rayleigh number shows that there is an inversion of the influence of the porosity parameter M on the heat transfer coefficient. With small values of Ra, with an increase in the parameter M, the heat transfer coefficient increases, since the temperature jump on the wall decreases. At Ra = 400, the effect of porosity is not observed. At high values of Ra, the intensity of heat transfer decreases but not so sharply as at low of Ra. That effect is caused from decreasing rate flow near the wall.

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16

SIERADZKI, A., A. CIZMAN, R. POPRAWSKI, T. MARCINISZYN und E. RYSIAKIEWICZ-PASEK. „ELECTRICAL CONDUCTIVITY AND PHASE TRANSITIONS IN KDP- AND ADP-POROUS GLASS NANOCOMPOSITES“. Journal of Advanced Dielectrics 01, Nr. 03 (Juli 2011): 337–43. http://dx.doi.org/10.1142/s2010135x11000471.

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The results of dielectric and dilatometric measurements of ADP and KDP-porous glass composites are presented. We stated on dilatometric studies that in ADP-porous glass nanocomposites the phase transition temperature decreases with decreasing of average size of pores. The negative jump of volume at phase transition region in ADP-porous glasses is observed. It was found that for KDP embedded into porous glasses nonmonotonous dependence of phase transition temperature on pores sizes occurs. The conductivity of ADP/KDP composites is significantly higher than in bulk crystals. The obtained values of activation energies are typical for proton movement.

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17

Prakash, Jai, und Chirala Satyanarayana. „Axisymmetric Slow Motion of a Porous Spherical Particle in a Viscous Fluid Using Time Fractional Navier–Stokes Equation“. Colloids and Interfaces 5, Nr. 2 (13.04.2021): 24. http://dx.doi.org/10.3390/colloids5020024.

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In this paper, we present the unsteady translational motion of a porous spherical particle in an incompressible viscous fluid. In this case, the modified Navier–Stokes equation with fractional order time derivative is used for conservation of momentum external to the particle whereas modified Brinkman equation with fractional order time derivative is used internal to the particle to govern the fluid flow. Stress jump condition for the tangential stress along with continuity of normal stress and continuity of velocity vectors is used at the porous–liquid interface. The integral Laplace transform technique is employed to solve the governing equations in fluid and porous regions. Numerical inversion code in MATLAB is used to obtain the solution of the problem in the physical domain. Drag force experienced by the particle is obtained. The numerical results have been discussed with the aid of graphs for some specific flows, namely damping oscillation, sine oscillation and sudden motion. Our result shows a significant contribution of the jump coefficient and the fractional order parameter to the drag force.

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18

Berjamin, Harold. „Nonlinear plane waves in saturated porous media with incompressible constituents“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, Nr. 2250 (Juni 2021): 20210086. http://dx.doi.org/10.1098/rspa.2021.0086.

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We consider the propagation of nonlinear plane waves in porous media within the framework of the Biot–Coussy biphasic mixture theory. The tortuosity effect is included in the model, and both constituents are assumed incompressible (Yeoh-type elastic skeleton, and saturating fluid). In this case, the linear dispersive waves governed by Biot’s theory are either of compression or shear-wave type, and nonlinear waves can be classified in a similar way. In the special case of a neo-Hookean skeleton, we derive the explicit expressions for the characteristic wave speeds, leading to the hyperbolicity condition. The sound speeds for a Yeoh skeleton are estimated using a perturbation approach. Then we arrive at the evolution equation for the amplitude of acceleration waves. In general, it is governed by a Bernoulli equation. With the present constitutive assumptions, we find that longitudinal jump amplitudes follow a nonlinear evolution, while transverse jump amplitudes evolve in an almost linearly degenerate fashion.

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19

Saad, E. I. „Axisymmetric motion of a spherical porous particle perpendicular to two parallel plates with slip surfaces“. Canadian Journal of Physics 93, Nr. 7 (Juli 2015): 784–95. http://dx.doi.org/10.1139/cjp-2014-0549.

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A combined analytical–numerical approach to the problem of the low Reynolds number motion of a porous sphere normal to one of two infinite parallel plates at an arbitrary position between them in a viscous fluid is investigated. The clear fluid motion governed by the Stokes equation and the Darcy–Brinkman equation is used to model the flow inside the porous material. The motion in each of the homogeneous regions is coupled with the continuity of the velocity components, the continuity of the normal stress, and the tangential stress jump condition. The fluid is allowed to slip at the surface of the walls. A general solution for the field equations in the clear region is constructed from the superposition of the fundamental solutions in both cylindrical and spherical coordinate systems. The collocation solutions for the hydrodynamic interactions between the porous sphere and the walls are calculated with good convergence for various values of the slip coefficient of the walls, the separation between the porous sphere and the walls, the stress jump coefficient, and a coefficient that is proportional to the permeability. For the special cases of a solid sphere, our drag results show excellent agreement with the available solutions in the literature for all relative particle-to-wall spacing.

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20

Zhou, Guoli, und Zhenting Hou. „The ergodicity of stochastic generalized porous media equations with lévy jump“. Acta Mathematica Scientia 31, Nr. 3 (Mai 2011): 925–33. http://dx.doi.org/10.1016/s0252-9602(11)60286-5.

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21

Srinivasacharya, D., und M. Krishna Prasad. „Creeping flow past a porous approximate sphere - Stress jump boundary condition“. ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik 91, Nr. 10 (26.04.2011): 824–31. http://dx.doi.org/10.1002/zamm.201000138.

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22

Prakash, Jai, G. P. Raja Sekhar und Mirela Kohr. „Stokes flow of an assemblage of porous particles: stress jump condition“. Zeitschrift für angewandte Mathematik und Physik 62, Nr. 6 (26.02.2011): 1027–46. http://dx.doi.org/10.1007/s00033-011-0123-6.

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23

Bhattacharyya, Anindita, und G. P. Raja Sekhar. „Stokes flow inside a porous spherical shell: Stress jump boundary condition“. Zeitschrift für angewandte Mathematik und Physik 56, Nr. 3 (Mai 2005): 475–96. http://dx.doi.org/10.1007/s00033-004-2115-2.

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24

Min, Jung Yim, und Sung Jin Kim. „A Novel Methodology for Thermal Analysis of a Composite System Consisting of a Porous Medium and an Adjacent Fluid Layer“. Journal of Heat Transfer 127, Nr. 6 (01.06.2005): 648–56. http://dx.doi.org/10.1115/1.1863273.

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An innovative methodology is presented for the purpose of analyzing fluid flow and heat transfer in a porous–fluid composite system, where the porous medium is assumed to have a periodic structure, i.e., solid and fluid phases repeat themselves in a regular pattern. With the present method, analytical solutions for the velocity and temperature distributions are obtained when the distributions in the adjacent fluid layer are allowed to vary in the directions both parallel and perpendicular to the interface between the porous medium and the adjacent fluid layer. The analytical solutions are validated by comparing them with the corresponding numerical solutions for the case of the ideal composite channel, and with existing experimental data. The present analytical solutions have a distinctive advantage in that they do not involve any unknown coefficients resulting from the previous interfacial conditions. Moreover, by comparing interfacial conditions derived from the present study with the stress- and flux-jump conditions developed by previous investigators, the unknown coefficients included in the stress- and flux-jump conditions are analytically determined and are shown to depend on the porosity, the Darcy number and the pore diameter.

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25

Low, Hong Tong, Xiao Bing Chen, Peng Yu und Sony Winoto. „Mass Transport in a Microchannel Bioreactor with a Porous Wall“. Applied Mechanics and Materials 110-116 (Oktober 2011): 3489–94. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3489.

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A two-dimensional flow model, incorporating mass transport, has been developed to simulate flow in a microchannel bioreactor with a porous wall. A two-domain method was implemented which was based on finite volume method. For the porous-fluid interface, a stress jump condition was used with continuity of normal stress; and the mass interfacial conditions were continuities of mass and mass flux. Two parameters are defined to characterize the mass transports in the fluid and porous regions. The porous Damkohler number is the ratio of consumption to diffusion of the substrates in the porous medium. The fluid Damkohler number is the ratio of substrate consumption in the porous medium to substrate convection in the fluid region. The concentration results are found to be well correlated by the use of a reaction-convection distance parameter which incorporates the effects of axial distance, substrate consumption and convection.

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Feichtner, Anna, Ed Mackay, Gavin Tabor, Philipp R. Thies und Lars Johanning. „Comparison of Macro-Scale Porosity Implementations for CFD Modelling of Wave Interaction with Thin Porous Structures“. Journal of Marine Science and Engineering 9, Nr. 2 (01.02.2021): 150. http://dx.doi.org/10.3390/jmse9020150.

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Computational fluid dynamics (CFD) modelling of wave interaction with thin perforated structures is of interest in a range of engineering applications. When large-scale effects such as forces and the overall flow behaviour are of interest, a microstructural resolution of the perforated geometry can be excessive or prohibitive in terms of computational cost. More efficiently, a thin porous structure can be represented by its macro-scale effects by means of a quadratic momentum source or pressure-drop respectively. In the context of regular wave interaction with thin porous structures and within an incompressible, two-phase Navier–Stokes and volume-of-fluid framework (based on interFoam of OpenFOAM®), this work investigates porosity representation as a porous surface with a pressure-jump condition and as volumetric isotropic and anisotropic porous media. Potential differences between these three types of macro-scale porosity implementations are assessed in terms of qualitative flow visualizations, velocity profiles along the water column, the wave elevation near the structures and the horizontal force on the structures. The comparison shows that all three types of implementation are capable of reproducing large-scale effects of the wave-structure interaction and that the differences between all obtained results are relatively small. It was found that the isotropic porous media implementation is numerically the most stable and requires the shortest computation times. The pressure-jump implementation requires the smallest time steps for stability and thus the longest computation times. This is likely due to the spurious local velocities at the air-water interface as a result of the volume-of-fluid interface capturing method combined with interFoam’s segregated pressure-velocity coupling algorithm. This paper provides useful insights and recommendations for effective macro-scale modelling of thin porous structures.

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Srinivascaharya, D., und M. Krishna Prasad. „Creeping flow past a porous approximately spherical shell: stress jump boundary condition“. ANZIAM Journal 52 (04.04.2012): 289. http://dx.doi.org/10.21914/anziamj.v52i0.4081.

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28

Sham, T. K., und I. Coulthard. „Edge-jump inversion in the SiL3,2-edge optical XAFS of porous silicon“. Journal of Synchrotron Radiation 6, Nr. 3 (01.05.1999): 215–16. http://dx.doi.org/10.1107/s0909049599001314.

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29

Valdés-Parada, Francisco J., Carlos G. Aguilar-Madera, J. Alberto Ochoa-Tapia und Benoît Goyeau. „Velocity and stress jump conditions between a porous medium and a fluid“. Advances in Water Resources 62 (Dezember 2013): 327–39. http://dx.doi.org/10.1016/j.advwatres.2013.08.008.

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30

Levy, A., G. Ben-Dor, S. Sorek und J. Bear. „Jump conditions across strong compaction waves in gas saturated rigid porous media“. Shock Waves 3, Nr. 2 (September 1993): 105–11. http://dx.doi.org/10.1007/bf02115890.

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31

Li, Ai-jun, Yong Liu und Hua-jun Li. „Accurate Solutions to Water Wave Scattering by Vertical Thin Porous Barriers“. Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/985731.

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The water wave scattering by vertical thin porous barriers is accurately solved in this study. Two typical structures of a surface-piercing barrier and a submerged bottom-standing barrier are considered. The solution procedure is based on the multi-term Galerkin method, in which the pressure jump across a porous barrier is expanded in a set of basis functions involving the Chebychev polynomials. Then, the square-root singularity of fluid velocity at the edge of the porous barrier is correctly modeled. The present solutions have the merits of very rapid convergence. Accurate results for both the reflection and the transmission coefficients and wave forces are presented. This study not only gives a promising procedure to tackle wave interaction with vertical thin porous barriers but also provides a reliable benchmark for complicated numerical solutions.

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FASANO, A., M. PRIMICERIO und D. TARZIA. „SIMILARITY SOLUTIONS IN A CLASS OF THAWING PROCESSES“. Mathematical Models and Methods in Applied Sciences 09, Nr. 01 (Februar 1999): 1–10. http://dx.doi.org/10.1142/s0218202599000026.

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A study on similarity solutions for a mathematical model for thawing in a saturated porous medium is considered when change of phase induces a density jump and the influence of pressure on the melting temperature is considered. The mathematical analysis is made for different cases, depending on the sign of the three physical parameters.

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Kimura, S., G. Schubert und J. M. Straus. „Instabilities of Steady, Periodic, and Quasi-Periodic Modes of Convection in Porous Media“. Journal of Heat Transfer 109, Nr. 2 (01.05.1987): 350–55. http://dx.doi.org/10.1115/1.3248087.

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Instabilities of steady and time-dependent thermal convection in a fluid-saturated porous medium heated from below have been studied using linear perturbation theory. The stability of steady-state solutions of the governing equations (obtained numerically) has been analyzed by evaluating the eigenvalues of the linearized system of equations describing the temporal behavior of infinitesimal perturbations. Using this procedure, we have found that time-dependent convection in a square cell sets in at Rayleigh number Ra=390. The temporal frequency of the simply periodic (P(1)) convection at Rayleigh numbers exceeding this value is given by the imaginary part of the complex eigenvalue. The stability of this (P(1)) state has also been studied; transition to quasi-periodic convection (QP2) occurs at Ra ≈ 510. A reverse transition to a simply periodic state (P(2)) occurs at Ra ≈ 560; a slight jump in the frequency of the P(2) state occurs at Ra between 625 and 640. The jump coincides with a second narrow (in terms of Ra) region of quasi-periodicity.

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Partha, M. K., P. V. Murthy und G. P. Raja Sekhar. „Viscous Flow Past a Porous Spherical Shell—Effect of Stress Jump Boundary Condition“. Journal of Engineering Mechanics 131, Nr. 12 (Dezember 2005): 1291–301. http://dx.doi.org/10.1061/(asce)0733-9399(2005)131:12(1291).

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35

Chandesris, M., und D. Jamet. „Derivation of jump conditions for the turbulence model at a fluid/porous interface“. International Journal of Heat and Fluid Flow 30, Nr. 2 (April 2009): 306–18. http://dx.doi.org/10.1016/j.ijheatfluidflow.2009.01.008.

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36

Torabi, Mohsen, Zhuomin Zhang und G. P. Peterson. „Interface entropy generation in micro porous channels with velocity slip and temperature jump“. Applied Thermal Engineering 111 (Januar 2017): 684–93. http://dx.doi.org/10.1016/j.applthermaleng.2016.09.148.

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37

Parthiban, C., und P. R. Patil. „Convection in a porous medium with velocity slip and temperature jump boundary conditions“. Heat and Mass Transfer 32, Nr. 1-2 (14.11.1996): 27–31. http://dx.doi.org/10.1007/s002310050087.

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38

Bovand, Masoud, Saman Rashidi, Masoomeh Dehesht und Javad Abolfazli Esfahani. „Effect of fluid-porous interface conditions on steady flow around and through a porous circular cylinder“. International Journal of Numerical Methods for Heat & Fluid Flow 25, Nr. 7 (07.09.2015): 1658–81. http://dx.doi.org/10.1108/hff-10-2014-0295.

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Purpose – The purpose of this paper is to implement the numerical analysis based on finite volume method to compare the effects of stress-jump (SJ) and stress-continuity (SC) conditions on flow structure around and through a porous circular cylinder. Design/methodology/approach – In this study, a steady flow of a viscous, incompressible fluid around and through a porous circular cylinder of diameter “D,” using Darcy-Brinkman-Forchheimer’s equation in the porous region, is discussed. The SJ condition proposed by Ochoa-Tapia and Whitaker is applied at the porous-fluid interface and compared with the traditional interfacial condition based on the SC condition in fluid and porous media. Equations with the relevant boundary conditions are numerically solved using a finite volume approach. In this study, Reynolds and Darcy numbers are varied within the ranges of 1 < Re < 40 and 10-7 < Da < 10-2, respectively, and the porosities are e=0.45, 0.7 and 0.95. Findings – Results show that the SJ condition leads to a much smaller boundary layer within porous medium near the interface as compared to the SC condition. Two interfacial conditions yield similar results with decrease in porosity. Originality/value – There is no published research in the literature about the effects of important parameters, such as Porosity and Darcy numbers on different fluid-porous interface conditions for a porous cylinder and comparison the effects of SJ and SC conditions on flow structure around and through a porous circular cylinder.

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Ramanuja, Mani, Gunduboina Gopi Krishna, Hari Kamala Sree und Vatukuru Naga Radhika. „Free Convection in a Vertical Slit Micro-channel with Super-hydrophobic Slip and Temperature Jump Conditions“. International Journal of Heat and Technology 38, Nr. 3 (15.10.2020): 738–44. http://dx.doi.org/10.18280/ijht.380318.

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The main objective of the convective incompressible fluid flow placed in a magnetic field, with vertical motion through an isothermally heated porous channel. The Super-hydrophobic the slip was applied on one wall along with temperature jump, while there is no slip on another wall. The analytical results are discussed qualitatively for the parameters which were on the mathematical formulation on the basis of the model equations designed for the linear momentum and energy balance. Decreasing the value of the slip parameter is noticed due to decreasing in temperature. The effects of heat source and porous medium on the micro channel flow is analysized in detail. Coparesion of current results is made with the earlier work. The effect of Dray parameter is to increase the fluid velocity in the channel.

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Kuznetsov, A. V. „Influence of the stress jump condition at the porous-medium/clear-fluid interface on a flow at a porous wall“. International Communications in Heat and Mass Transfer 24, Nr. 3 (Mai 1997): 401–10. http://dx.doi.org/10.1016/s0735-1933(97)00025-0.

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41

Leont’ev, N. E. „Contamination of a porous bed by a moving front with a finite porosity jump“. Moscow University Mechanics Bulletin 64, Nr. 5 (Oktober 2009): 130–34. http://dx.doi.org/10.3103/s0027133009050070.

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42

Rashidi, S., A. Nouri-Borujerdi, M. S. Valipour, R. Ellahi und I. Pop. „Stress-jump and Continuity Interface Conditions for a Cylinder Embedded in a Porous Medium“. Transport in Porous Media 107, Nr. 1 (12.12.2014): 171–86. http://dx.doi.org/10.1007/s11242-014-0431-3.

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43

Syamsuri, Ming-Jyh Chern und Nima Vaziri. „Effect of Porous Media on Hydraulic Jump Characteristics by Using Smooth Particle Hydrodynamics Method“. International Journal of Civil Engineering 18, Nr. 3 (23.10.2019): 367–79. http://dx.doi.org/10.1007/s40999-019-00465-8.

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Wang, Yunpeng, und Roger E. Khayat. „The planar spread of a liquid jet and hydraulic jump on a porous layer“. Physics of Fluids 33, Nr. 1 (01.01.2021): 012104. http://dx.doi.org/10.1063/5.0033640.

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Wang, Zhi Jian, Tian Zhu Zhang, Jin Shang und Metsakeu Kong Evariste. „Precision Compound Sand Control Screen Internal Flow Field of the CFD Simulation“. Applied Mechanics and Materials 644-650 (September 2014): 4682–85. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.4682.

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In this paper, calculating fluid dynamics (CFD) method is utilized for analyzing the precision compound sand control screen internal flow field so as to establish appropriate models. During this numerical calculation, by using the - turbulence model is used to simulate the resistance characteristics under different working conditions when crude oil flows through precision compound sand control screen, analyze its speed change rule, flow path and pressure distribution, etc. The use of porous media model to simulate the resistance of the oil screen effect, the oil screen is replaced by the porous jump surface to simulate the strainer of pressure drop. To screen sand control performance and reduce the flow resistance to provide theoretical support, make the reservoir production losses to a minimum.

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Aina, Babatunde, und Peter Bukar Malgwi. „MHD Convection Fluid and Heat Transfer in an Inclined Micro-Porous-Channel“. Nonlinear Engineering 8, Nr. 1 (28.01.2019): 755–63. http://dx.doi.org/10.1515/nleng-2018-0081.

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Abstract This study is devoted to investigate the influence of transverse magnetic field as well as suction/injection on MHD natural convection flow of conducting fluid in an inclined micro-porous-channel. The analytical solutions for velocity profile and temperature profile have been obtained considering the velocity slip and temperature jump conditions at the micro-porous-channel walls. The solution obtained for the velocity has been used to compute the skin friction, while the temperature has been used to compute the Nusselt number. The effect of various flow parameters entering into the problem are discussed with the aid of line graphs. Results reveal that the impact of inclination angle on fluid velocity is dependent on the value of the wall ambient temperature difference ratio, hence increase in inclination angle yields an enhancement in fluid velocity within the micro-porous-channel for some selected values of the wall ambient temperature difference ratio whereas it displays a dual character for other values. Also, injecting through the micro-porous channel thickens the thermal boundary layer, resulting to weakening the convective current and consequently decreasing the fluid velocity whereas suction weakens the thermal boundary layer yielding an increase in fluid velocity.

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Titiloye, E. O., J. A. Gbadeyan und A. T. Adeosun. „An Oscillatory Radiating Hydromagnetic Internal Heat Generating Fluid Flow Through a Vertcal Porous Channel with Slip and Temperature Jump“. International Journal of Applied Mechanics and Engineering 23, Nr. 2 (01.05.2018): 503–19. http://dx.doi.org/10.2478/ijame-2018-0029.

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Abstract The present study concerns the natural convective heat generating/absorbing, radiative magnetohydrodynamic, oscillatory fluid flow through a vertical porous channel with slip and temperature jump. The effect of Joule dissipation is taken into consideration while it is assumed that the flow is fully developed. The differential transforms method(DTM) is employed to solve the system of non-linear ordinary differential equations that is obtained from the non-linear partial differential equations governing the flow. Semi analytical solutions of the steady and unsteady part of the flow in the slip flow regime through a vertical porous channel are obtained. The effects of various flow parameters on the velocity and temperature profiles as well as Nusselt and skin friction are presented graphically and discussed. An excellent agreement between the results of this article and those available in the literature validated the presented approach.

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Carraro, T., C. Goll, A. Marciniak-Czochra und A. Mikelić. „Pressure jump interface law for the Stokes–Darcy coupling: confirmation by direct numerical simulations“. Journal of Fluid Mechanics 732 (12.09.2013): 510–36. http://dx.doi.org/10.1017/jfm.2013.416.

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AbstractIt is generally accepted that the effective velocity of a viscous flow over a porous bed satisfies the Beavers–Joseph slip law. To the contrary, the interface law for the effective stress has been a subject of controversy. Recently, a pressure jump interface law has been rigourously derived by Marciniak-Czochra and Mikelić. In this paper, we provide a confirmation of the analytical result using direct numerical simulation of the flow at the microscopic level. To the best of the authors’ knowledge, this is the first numerical confirmation of the pressure interface law in the literature.

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Al-khliefat, V., und H. Duwairi. „DARCIAN VELOCITY AND TEMPERATURE JUMP EFFECTS ON CONVECTION FROM VERTICAL SURFACE EMBEDDED IN POROUS MEDIA“. International Journal of Heat and Technology 33, Nr. 2 (30.06.2015): 97–102. http://dx.doi.org/10.18280/ijht.330216.

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50

Silva, Renato A., und Marcelo J. S. de Lemos. „NUMERICAL ANALYSIS OF THE STRESS JUMP INTERFACE CONDITION FOR LAMINAR FLOW OVER A POROUS LAYER“. Numerical Heat Transfer, Part A: Applications 43, Nr. 6 (Mai 2003): 603–17. http://dx.doi.org/10.1080/10407780307351.

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