The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
R. Letan - One of the best experts on this subject based on the ideXlab platform.
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melting in a vertical Cylindrical Tube numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:Abstract The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results . The numerical analysis is realized using an enthalpy–porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure–velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role. Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom.
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Melting in a vertical Cylindrical Tube: Numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results .The numerical analysis is realized using an enthalpy-porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure-velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role.Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom. © 2010 Elsevier Ltd.
R W Ogden - One of the best experts on this subject based on the ideXlab platform.
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waves and vibrations in a finitely deformed electroelastic circular Cylindrical Tube
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2020Co-Authors: Luis Dorfmann, R W OgdenAbstract:In two recent papers, conditions for which axisymmetric incremental bifurcation could arise for a circular Cylindrical Tube subject to axial extension and radial inflation in the presence of an axi...
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finite deformations of an electroelastic circular Cylindrical Tube
Zeitschrift für Angewandte Mathematik und Physik, 2016Co-Authors: Andrey Melnikov, R W OgdenAbstract:In this paper the theory of nonlinear electroelasticity is used to examine deformations of a pressurized thick-walled circular Cylindrical Tube of soft dielectric material with closed ends and compliant electrodes on its curved boundaries. Expressions for the dependence of the pressure and reduced axial load on the deformation and a potential difference between, or uniform surface charge distributions on, the electrodes are obtained in respect of a general isotropic electroelastic energy function. To illustrate the behaviour of the Tube, specific forms of energy functions accounting for different mechanical properties coupled with a deformation independent quadratic dependence on the electric field are used for numerical purposes, for a given potential difference and separately for a given charge distribution. Numerical dependences of the non-dimensional pressure and reduced axial load on the deformation are obtained for the considered energy functions. Results are then given for the thin-walled approximation as a limiting case of a thick-walled Cylindrical Tube without restriction on the energy function. The theory described herein provides a general basis for the detailed analysis of the electroelastic response of tubular dielectric elastomer actuators, which is illustrated for a fixed axial load in the absence of internal pressure and fixed internal pressure in the absence of an applied axial load.
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extension inflation and torsion of a residually stressed circular Cylindrical Tube
Continuum Mechanics and Thermodynamics, 2016Co-Authors: J Merodio, R W OgdenAbstract:In this paper, we provide a new example of the solution of a finite deformation boundary-value problem for a residually stressed elastic body. Specifically, we analyse the problem of the combined extension, inflation and torsion of a circular Cylindrical Tube subject to radial and circumferential residual stresses and governed by a residual-stress dependent nonlinear elastic constitutive law. The problem is first of all formulated for a general elastic strain-energy function, and compact expressions in the form of integrals are obtained for the pressure, axial load and torsional moment required to maintain the given deformation. For two specific simple prototype strain-energy functions that include residual stress, the integrals are evaluated to give explicit closed-form expressions for the pressure, axial load and torsional moment. The dependence of these quantities on a measure of the radial strain is illustrated graphically for different values of the parameters (in dimensionless form) involved, in particular the Tube thickness, the amount of torsion and the strength of the residual stress. The results for the two strain-energy functions are compared and also compared with results when there is no residual stress.
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loss of ellipticity in the combined helical axial and radial elastic deformations of a fibre reinforced circular Cylindrical Tube
International Journal of Solids and Structures, 2015Co-Authors: Mustapha El Hamdaoui, José Merodio, R W OgdenAbstract:In this paper we consider theoretically the finite deformation of a circular Cylindrical Tube of a transversely isotropic elastic material, specifically the combined axial stretch, inflation and helical shear deformation, with particular reference to the failure of ellipticity. For a simple form of strain-energy function specific examples involving axial and radial directions of transverse isotropy are then considered, leading to different predictions of the onset of ellipticity failure.
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on deforming a sector of a circular Cylindrical Tube into an intact Tube existence uniqueness and stability
International Journal of Engineering Science, 2010Co-Authors: R W Ogden, Michel Destrade, Jeremiah G MurphyAbstract:Within the context of finite deformation elasticity theory the problem of deforming an open sector of a thick-walled circular Cylindrical Tube into a complete circular Cylindrical Tube is analyzed. The analysis provides a means of estimating the radial and circumferential residual stress present in an intact Tube, which is a problem of particular concern in dealing with the mechanical response of arteries. The initial sector is assumed to be unstressed and the stress distribution resulting from the closure of the sector is then calculated in the absence of loads on the Cylindrical surfaces. Conditions on the form of the elastic strain-energy function required for existence and uniqueness of the deformed configuration are then examined. Finally, stability of the resulting finite deformation is analyzed using the theory of incremental deformations superimposed on the finite deformation, implemented in terms of the Stroh formulation. The main results are that convexity of the strain energy as a function of a certain deformation variable ensures existence and uniqueness of the residually-stressed intact Tube, and that bifurcation can occur in the closing of thick, widely opened sectors, depending on the values of geometrical and physical parameters. The results are illustrated for particular choices of these parameters, based on data available in the biomechanics literature.
H. Shmueli - One of the best experts on this subject based on the ideXlab platform.
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melting in a vertical Cylindrical Tube numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:Abstract The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results . The numerical analysis is realized using an enthalpy–porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure–velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role. Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom.
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Melting in a vertical Cylindrical Tube: Numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results .The numerical analysis is realized using an enthalpy-porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure-velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role.Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom. © 2010 Elsevier Ltd.
Sejin Yook - One of the best experts on this subject based on the ideXlab platform.
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three dimensional inverse heat conduction modeling of a multi layered hollow Cylindrical Tube using input estimation algorithm and thermal resistance network
International Journal of Heat and Mass Transfer, 2017Co-Authors: Sejin YookAbstract:Abstract High-temperature gas flow can cause melt, crack, erosion, and wear of Tubes. In order to reduce these side effects, the inner wall of a hollow Cylindrical Tube is generally coated with a resistive material, for example, a steel pipe coated with a chrome layer. In addition, it is important to know heat flux applied to the Tube wall and temperature distribution in the Tube wall for appropriate design of the hollow Cylindrical Tube. In this study, three-dimensional inverse heat conduction modeling of a multi-layered hollow Cylindrical Tube was conducted. The thermal resistance network (TRN) scheme was employed to solve the heat conduction in the Tube. The temperature distribution in the Tube was estimated from a measured temperature on the outer wall of the Tube by Kalman filter. At the same time, unknown heat flux on the inner wall of the Tube was calculated by the recursive least squares algorithm.
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prediction of time varying heat flux along a hollow Cylindrical Tube wall using recursive input estimation algorithm and thermal resistance network method
International Journal of Heat and Mass Transfer, 2016Co-Authors: Sejin YookAbstract:Abstract In this study, a model using the thermal resistance network method and the recursive input estimation algorithm was developed to analyze two-dimensional inverse heat conduction problems. The recursive input estimation algorithm consisted of the Kalman filter and the real-time least squares. A two-layered hollow Cylindrical Tube was assumed with the convection heat transfer boundary condition at the outer wall of the Tube. Using the model developed in this study, an unknown time-varying heat flux at the inner wall of the Tube was predicted from the known temperatures at some positions on the outer wall of the Tube in the longitudinal direction. In the process of predicting the unknown heat flux, the temperature distribution in the two-layered hollow Cylindrical Tube wall was also obtained. The present model was able to accurately predict the unknown time-varying heat flux profiles of square waves or sinusoidal-like waves with and without spatial variations in the longitudinal direction.
G. Ziskind - One of the best experts on this subject based on the ideXlab platform.
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melting in a vertical Cylindrical Tube numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:Abstract The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results . The numerical analysis is realized using an enthalpy–porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure–velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role. Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom.
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Melting in a vertical Cylindrical Tube: Numerical investigation and comparison with experiments
International Journal of Heat and Mass Transfer, 2010Co-Authors: H. Shmueli, G. Ziskind, R. LetanAbstract:The present work numerically investigates melting of a phase-change material (PCM) in a vertical Cylindrical Tube. The analysis aims at an investigation of local flow and thermal phenomena, by means of a numerical simulation which is compared to the previous experimental results .The numerical analysis is realized using an enthalpy-porosity formulation. The effect of various parameters of the numerical solution on the results is examined: in particular, the term describing the mushy zone in the momentum equation and the influence of the pressure-velocity coupling and pressure discretization schemes. PISO vs. SIMPLE and PRESTO! vs. Body-Force-Weighted schemes are examined. No difference is detected between the first two. However, considerable differences appear with regard to the last two, due to the mushy zone role.Image processing of experimental results from the previous studies is performed, yielding quantitative information about the local melt fractions and heat transfer rates. Based on the good agreement between simulations and experiments, the work compares the heat transfer rates from the experiments with those from the numerical analysis, providing a deeper understanding of the heat transfer mechanisms. The results show quantitatively that at the beginning of the process, the heat transfer is by conduction from the Tube wall to the solid phase through a relatively thin liquid layer. As the melting progresses, natural convection in the liquid becomes dominant, changing the solid shape to a conical one, which shrinks in size from the top to the bottom. © 2010 Elsevier Ltd.
