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Mikhail A Sheremet - One of the best experts on this subject based on the ideXlab platform.
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natural convection of cuo water micropolar nanofluids inside a porous enclosure using local thermal non equilibrium condition
Journal of The Taiwan Institute of Chemical Engineers, 2018Co-Authors: Mohsen Izadi, S A M Mehryan, Mikhail A SheremetAbstract:Abstract The present paper deals with numerical investigation of natural convection of a micropolar nanofluid inside a porous enclosure using thermal non-equilibrium model. Rates of the heat transfer and micropolar nanofluid flow are widely considered by presenting contours of nanofluid flow, isotherms of fluid and solid phases, and contours of micro-rotation. Numerical results have been validated with previous references and good concordance has been observed. The results confirm that the thermal non-equilibrium model of the porous medium approaches the thermal equilibrium one by increasing thermal conductivity ratio Parameter as well as the heat transfer Interface Parameter. The strength of convection inside pores of porous medium arises from augmenting H that can result in micro-rotations amplification. The characteristic equations of a micropolar fluid flow are transformed into classic Navier–Stokes equations by increasing porosity and the dimension of pores. Results indicate that the reduction of the thermal resistance of the fluid phase due to an increment of Kr can enhance the heat transfer rate through porous media. Finally, the permeability is important and influences the Nusselt numbers of both the solid matrix and the nanofluid when the nanofluid particles rotate around the center of their gravity.
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analysis of conjugate natural convection within a porous square enclosure occupied with micropolar nanofluid using local thermal non equilibrium model
Journal of Molecular Liquids, 2018Co-Authors: S A M Mehryan, Mohsen Izadi, Mikhail A SheremetAbstract:Abstract This work aims to study the conjugate natural convection of micropolar nanofluid within a porous enclosure considering local thermal non-equilibrium model. The Galerkin finite element method is employed to solve the coupled and non-linear equations. The governing Parameters are Darcy–Rayleigh number Ra = 10–1000, porosity e = 0.1–0.9, Interface Parameter H = 1–1000, Kr = 0.1–10, volume fraction of the nanofluid φnf = 0–0.08, vortex viscosity Parameter Δ = 0–3, the width of the solid wall d = 0.1–0.4 and ratio of wall thermal conductivity to that of the base fluid Rk = 0.1–10. It has been revealed that the power of micro-rotations increases with Darcy–Rayleigh number, vortex viscosity Parameter, ratio of wall thermal conduction to that of base fluid, Interface Parameter (Kr and H) in conditions that declines with thickness of the solid wall and porosity. The Nusselt numbers for both phases in the porous medium significantly decline as thickness of the solid wall rises, with the exception of d = 0.35. Also, it can be concluded as the porosity Parameter increases for the passing flow, the nanofluid flow is governed by the classic Navier-Stokes equations.
Mohsen Izadi - One of the best experts on this subject based on the ideXlab platform.
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conjugate natural convection of nanofluids inside an enclosure filled by three layers of solid porous medium and free nanofluid using buongiorno s and local thermal non equilibrium models
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: S A M Mehryan, Mohammad Ghalambaz, Mohsen IzadiAbstract:The natural convective heat transfer of nanofluids was addressed inside a square enclosure filled by three different layers: solid, porous medium and free fluid. The behavior of the porous layer has been simulated using local thermal non-equilibrium model. The Buongiorno’s model was utilized to evaluate the distribution of nanoparticles inside the enclosure that arose from the thermophoresis and Brownian motion. The governing equations were solved by the Galerkin finite element method in a non-uniform grid. The governing Parameters are Rayleigh number Ra = 103–106, porosity e = 0.3–0.9, Darcy number Da = 10−5–10−2, Interface Parameter Kr = 0.1–10, H = 0.1–1000; ratio of wall thermal conductivity to that of the nanofluid, Rk = 0.1–10, dimensionless length of the heater B = 0.2–0.8; dimensionless centre position height of the heater Z = 0.3–0.7 and Lewis number Le = 10–100. A considerable concentration gradient of nanoparticles was found inside the enclosure. In some studied cases, the non-dimensional volume fraction of nanoparticles is about 10% higher than the average volume fraction of nanoparticles at the region near the cold wall. The variability of Darcy and the Rayleigh numbers indicated significant effects on heat transfer rate and the concentration patterns of the nanoparticles and inward the cavity. The increase in Le and Nr amplifies and decreases the heat transfer rates through fluid and solid phases, respectively. In addition, it can be seen that the increment in heat transfer rates with Le increases as Nr increases.
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natural convection of cuo water micropolar nanofluids inside a porous enclosure using local thermal non equilibrium condition
Journal of The Taiwan Institute of Chemical Engineers, 2018Co-Authors: Mohsen Izadi, S A M Mehryan, Mikhail A SheremetAbstract:Abstract The present paper deals with numerical investigation of natural convection of a micropolar nanofluid inside a porous enclosure using thermal non-equilibrium model. Rates of the heat transfer and micropolar nanofluid flow are widely considered by presenting contours of nanofluid flow, isotherms of fluid and solid phases, and contours of micro-rotation. Numerical results have been validated with previous references and good concordance has been observed. The results confirm that the thermal non-equilibrium model of the porous medium approaches the thermal equilibrium one by increasing thermal conductivity ratio Parameter as well as the heat transfer Interface Parameter. The strength of convection inside pores of porous medium arises from augmenting H that can result in micro-rotations amplification. The characteristic equations of a micropolar fluid flow are transformed into classic Navier–Stokes equations by increasing porosity and the dimension of pores. Results indicate that the reduction of the thermal resistance of the fluid phase due to an increment of Kr can enhance the heat transfer rate through porous media. Finally, the permeability is important and influences the Nusselt numbers of both the solid matrix and the nanofluid when the nanofluid particles rotate around the center of their gravity.
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analysis of conjugate natural convection within a porous square enclosure occupied with micropolar nanofluid using local thermal non equilibrium model
Journal of Molecular Liquids, 2018Co-Authors: S A M Mehryan, Mohsen Izadi, Mikhail A SheremetAbstract:Abstract This work aims to study the conjugate natural convection of micropolar nanofluid within a porous enclosure considering local thermal non-equilibrium model. The Galerkin finite element method is employed to solve the coupled and non-linear equations. The governing Parameters are Darcy–Rayleigh number Ra = 10–1000, porosity e = 0.1–0.9, Interface Parameter H = 1–1000, Kr = 0.1–10, volume fraction of the nanofluid φnf = 0–0.08, vortex viscosity Parameter Δ = 0–3, the width of the solid wall d = 0.1–0.4 and ratio of wall thermal conductivity to that of the base fluid Rk = 0.1–10. It has been revealed that the power of micro-rotations increases with Darcy–Rayleigh number, vortex viscosity Parameter, ratio of wall thermal conduction to that of base fluid, Interface Parameter (Kr and H) in conditions that declines with thickness of the solid wall and porosity. The Nusselt numbers for both phases in the porous medium significantly decline as thickness of the solid wall rises, with the exception of d = 0.35. Also, it can be concluded as the porosity Parameter increases for the passing flow, the nanofluid flow is governed by the classic Navier-Stokes equations.
A. Mioduchowski - One of the best experts on this subject based on the ideXlab platform.
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new phenomena concerning the effect of imperfect bonding on radial matrix cracking in fiber composites
International Journal of Engineering Science, 2001Co-Authors: Y Liu, Peter Schiavone, A. MioduchowskiAbstract:Abstract In this paper we study the effects of imperfect bonding on stress intensity factors (SIFs) calculated at a radial matrix crack in a fiber (inclusion) composite subjected to various cases of mechanical loading. We use analytic continuation to adapt and extend the existing series methods to obtain series representations of deformation and stress fields in both the inclusion and the surrounding matrix in the presence of the crack. The interaction between the crack and the inclusion is demonstrated numerically for different elastic materials, geometries and varying degrees of bonding (represented by imperfect Interface Parameters) at the Interface. Some qualitatively new phenomena are predicted for radial matrix cracking, specifically the influence of imperfect bonding at the inclusion–matrix Interface on the direction of crack growth. For example, in the case of an inclusion perfectly bonded to the surrounding matrix, the SIF at the nearby crack tip is greater than that at the distant crack tip only when the inclusion is more compliant than the matrix. In contrast, the effects of imperfect bonding at the inclusion–matrix Interface allow for the SIF at the nearby crack tip to be greater than that at the distant crack tip even when the inclusion is stiffer than the matrix . In fact, for any given case when the inclusion is stiffer than the matrix, we show that there is a corresponding critical value of the imperfect Interface Parameter below which a radial matrix crack grows towards the Interface leading eventually to complete debonding. In particular, this critical value of the imperfect Interface Parameter tends to a non-zero finite value when the stiffness of the inclusion approaches infinity. To our knowledge, these results provide, for the first time, a clear quantitative description of the relationship between Interface imperfections and the direction of propagation of radial matrix cracks.
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Stress Analysis of an Elliptic Inclusion with Imperfect Interface in Plane Elasticity
Journal of elasticity and the physical science of solids, 2001Co-Authors: H. Shen, P. Schiavone, A. MioduchowskiAbstract:In this paper, a semi-analytic solution of the problem associated with an elliptic inclusion embedded within an infinite matrix is developed for plane strain deformations. The bonding at the inclusion-matrix Interface is assumed to be homogeneously imperfect. The Interface is modeled as a spring (interphase) layer with vanishing thickness. The behavior of this interphase layer is based on the assumption that tractions are continuous but displacements are discontinuous across the Interface. Complex variable techniques are used to obtain infinite series representations of the stresses which, when evaluated numerically, demonstrate how the peak stress along the inclusion-matrix Interface and the average stress inside the inclusion vary with the aspect ratio of the inclusion and a representative Parameter h (related to the two Interface Parameters describing the imperfect Interface in two-dimensional elasticity) characterizing the imperfect Interface. In addition, and perhaps most significantly, for different aspect ratios of the elliptic inclusion, we identify a specific value ( h ^*) of the (representative) Interface Parameter h which corresponds to maximum peak stress along the inclusion-matrix Interface. Similarly, for each aspect ratio, we identify a specific value of h (also referred to as h ^* in the paper) which corresponds to maximum peak strain energy density along the Interface, as defined by Achenbach and Zhu (1990). In each case, we plot the relationship between the new Parameter h ^*and the aspect ratio of the ellipse. This gives significant and valuable information regarding the failure of the Interface using two established failure criteria.
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an elliptic inclusion with imperfect Interface in anti plane shear
International Journal of Solids and Structures, 2000Co-Authors: Peter Schiavone, H. Shen, A. MioduchowskiAbstract:Abstract A semi-analytic solution is developed for the problem associated with an elliptic inclusion embedded within an infinite matrix in anti-plane shear. The bonding at the inclusion-matrix Interface is assumed to be homogeneously imperfect. The Interface is modeled as a spring (interphase) layer with vanishing thickness. The behaviour of this interphase layer is based on the assumption that tractions are continuous but displacements are discontinuous across the Interface. Complex variable techniques are used to obtain infinite series representations of the stresses induced within the inclusion. The results obtained demonstrate how the (non-uniform) stress field and the average stresses inside the inclusion vary with the aspect ratio of the inclusion and the Parameter describing the imperfect Interface. In addition, it is shown that, in some cases (depending on the aspect ratio of the ellipse), it is possible to identify specific values of the Interface Parameter which correspond to maximum peak stress along the Interface.
S A M Mehryan - One of the best experts on this subject based on the ideXlab platform.
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conjugate natural convection of nanofluids inside an enclosure filled by three layers of solid porous medium and free nanofluid using buongiorno s and local thermal non equilibrium models
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: S A M Mehryan, Mohammad Ghalambaz, Mohsen IzadiAbstract:The natural convective heat transfer of nanofluids was addressed inside a square enclosure filled by three different layers: solid, porous medium and free fluid. The behavior of the porous layer has been simulated using local thermal non-equilibrium model. The Buongiorno’s model was utilized to evaluate the distribution of nanoparticles inside the enclosure that arose from the thermophoresis and Brownian motion. The governing equations were solved by the Galerkin finite element method in a non-uniform grid. The governing Parameters are Rayleigh number Ra = 103–106, porosity e = 0.3–0.9, Darcy number Da = 10−5–10−2, Interface Parameter Kr = 0.1–10, H = 0.1–1000; ratio of wall thermal conductivity to that of the nanofluid, Rk = 0.1–10, dimensionless length of the heater B = 0.2–0.8; dimensionless centre position height of the heater Z = 0.3–0.7 and Lewis number Le = 10–100. A considerable concentration gradient of nanoparticles was found inside the enclosure. In some studied cases, the non-dimensional volume fraction of nanoparticles is about 10% higher than the average volume fraction of nanoparticles at the region near the cold wall. The variability of Darcy and the Rayleigh numbers indicated significant effects on heat transfer rate and the concentration patterns of the nanoparticles and inward the cavity. The increase in Le and Nr amplifies and decreases the heat transfer rates through fluid and solid phases, respectively. In addition, it can be seen that the increment in heat transfer rates with Le increases as Nr increases.
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natural convection of cuo water micropolar nanofluids inside a porous enclosure using local thermal non equilibrium condition
Journal of The Taiwan Institute of Chemical Engineers, 2018Co-Authors: Mohsen Izadi, S A M Mehryan, Mikhail A SheremetAbstract:Abstract The present paper deals with numerical investigation of natural convection of a micropolar nanofluid inside a porous enclosure using thermal non-equilibrium model. Rates of the heat transfer and micropolar nanofluid flow are widely considered by presenting contours of nanofluid flow, isotherms of fluid and solid phases, and contours of micro-rotation. Numerical results have been validated with previous references and good concordance has been observed. The results confirm that the thermal non-equilibrium model of the porous medium approaches the thermal equilibrium one by increasing thermal conductivity ratio Parameter as well as the heat transfer Interface Parameter. The strength of convection inside pores of porous medium arises from augmenting H that can result in micro-rotations amplification. The characteristic equations of a micropolar fluid flow are transformed into classic Navier–Stokes equations by increasing porosity and the dimension of pores. Results indicate that the reduction of the thermal resistance of the fluid phase due to an increment of Kr can enhance the heat transfer rate through porous media. Finally, the permeability is important and influences the Nusselt numbers of both the solid matrix and the nanofluid when the nanofluid particles rotate around the center of their gravity.
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analysis of conjugate natural convection within a porous square enclosure occupied with micropolar nanofluid using local thermal non equilibrium model
Journal of Molecular Liquids, 2018Co-Authors: S A M Mehryan, Mohsen Izadi, Mikhail A SheremetAbstract:Abstract This work aims to study the conjugate natural convection of micropolar nanofluid within a porous enclosure considering local thermal non-equilibrium model. The Galerkin finite element method is employed to solve the coupled and non-linear equations. The governing Parameters are Darcy–Rayleigh number Ra = 10–1000, porosity e = 0.1–0.9, Interface Parameter H = 1–1000, Kr = 0.1–10, volume fraction of the nanofluid φnf = 0–0.08, vortex viscosity Parameter Δ = 0–3, the width of the solid wall d = 0.1–0.4 and ratio of wall thermal conductivity to that of the base fluid Rk = 0.1–10. It has been revealed that the power of micro-rotations increases with Darcy–Rayleigh number, vortex viscosity Parameter, ratio of wall thermal conduction to that of base fluid, Interface Parameter (Kr and H) in conditions that declines with thickness of the solid wall and porosity. The Nusselt numbers for both phases in the porous medium significantly decline as thickness of the solid wall rises, with the exception of d = 0.35. Also, it can be concluded as the porosity Parameter increases for the passing flow, the nanofluid flow is governed by the classic Navier-Stokes equations.
Peter Schiavone - One of the best experts on this subject based on the ideXlab platform.
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uniform strain field inside a non circular inhomogeneity with homogeneously imperfect Interface in anisotropic anti plane shear
Zeitschrift für Angewandte Mathematik und Physik, 2016Co-Authors: Peter Schiavone, Ming Dai, Cunfa GaoAbstract:We re-examine the conclusion established earlier in the literature that in the presence of a homogeneously imperfect Interface, the circular inhomogeneity is the only shape of inhomogeneity which can achieve a uniform internal strain field in an isotropic or anisotropic material subjected to anti-plane shear. We show that under certain conditions, it is indeed possible to design such non-circular inhomogeneities despite the limitation of a homogeneously imperfect Interface. Our method proceeds by prescribing a uniform strain field inside a non-circular inhomogeneity via perturbations of the uniform strain field inside the analogous circular inhomogeneity and then subsequently identifying the corresponding (non-circular) shape via the use of a conformal mapping whose unknown coefficients are determined from a system of nonlinear equations. We illustrate our results with several examples. We note also that, for a given size of inhomogeneity, the minimum value of the Interface Parameter required to guarantee the desired uniform internal strain increases as the elastic constants of the inclusion approach those of the matrix. Finally, we discuss in detail the relationship between the curvature of the Interface and the displacement jump across the Interface in the design of such inhomogeneities.
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new phenomena concerning the effect of imperfect bonding on radial matrix cracking in fiber composites
International Journal of Engineering Science, 2001Co-Authors: Y Liu, Peter Schiavone, A. MioduchowskiAbstract:Abstract In this paper we study the effects of imperfect bonding on stress intensity factors (SIFs) calculated at a radial matrix crack in a fiber (inclusion) composite subjected to various cases of mechanical loading. We use analytic continuation to adapt and extend the existing series methods to obtain series representations of deformation and stress fields in both the inclusion and the surrounding matrix in the presence of the crack. The interaction between the crack and the inclusion is demonstrated numerically for different elastic materials, geometries and varying degrees of bonding (represented by imperfect Interface Parameters) at the Interface. Some qualitatively new phenomena are predicted for radial matrix cracking, specifically the influence of imperfect bonding at the inclusion–matrix Interface on the direction of crack growth. For example, in the case of an inclusion perfectly bonded to the surrounding matrix, the SIF at the nearby crack tip is greater than that at the distant crack tip only when the inclusion is more compliant than the matrix. In contrast, the effects of imperfect bonding at the inclusion–matrix Interface allow for the SIF at the nearby crack tip to be greater than that at the distant crack tip even when the inclusion is stiffer than the matrix . In fact, for any given case when the inclusion is stiffer than the matrix, we show that there is a corresponding critical value of the imperfect Interface Parameter below which a radial matrix crack grows towards the Interface leading eventually to complete debonding. In particular, this critical value of the imperfect Interface Parameter tends to a non-zero finite value when the stiffness of the inclusion approaches infinity. To our knowledge, these results provide, for the first time, a clear quantitative description of the relationship between Interface imperfections and the direction of propagation of radial matrix cracks.
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an elliptic inclusion with imperfect Interface in anti plane shear
International Journal of Solids and Structures, 2000Co-Authors: Peter Schiavone, H. Shen, A. MioduchowskiAbstract:Abstract A semi-analytic solution is developed for the problem associated with an elliptic inclusion embedded within an infinite matrix in anti-plane shear. The bonding at the inclusion-matrix Interface is assumed to be homogeneously imperfect. The Interface is modeled as a spring (interphase) layer with vanishing thickness. The behaviour of this interphase layer is based on the assumption that tractions are continuous but displacements are discontinuous across the Interface. Complex variable techniques are used to obtain infinite series representations of the stresses induced within the inclusion. The results obtained demonstrate how the (non-uniform) stress field and the average stresses inside the inclusion vary with the aspect ratio of the inclusion and the Parameter describing the imperfect Interface. In addition, it is shown that, in some cases (depending on the aspect ratio of the ellipse), it is possible to identify specific values of the Interface Parameter which correspond to maximum peak stress along the Interface.