The Experts below are selected from a list of 20256 Experts worldwide ranked by ideXlab platform
Bryan M. Wong - One of the best experts on this subject based on the ideXlab platform.
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large scale atomistic simulations of helium 3 Bubble Growth in complex palladium alloys
Journal of Chemical Physics, 2016Co-Authors: Lucas M Hale, Jonathan A. Zimmerman, Bryan M. WongAbstract:Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material’s structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and Growth of helium-3 Bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium Bubble Growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how ...
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large scale atomistic simulations of helium 3 Bubble Growth in complex palladium alloys
Journal of Chemical Physics, 2016Co-Authors: Lucas M Hale, Jonathan A. Zimmerman, Bryan M. WongAbstract:Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material's structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and Growth of helium-3 Bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium Bubble Growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how and why our developed potentials either meet or confound these expectations.
Yuying Yan - One of the best experts on this subject based on the ideXlab platform.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part i experiments and 1 d modelling
International Journal of Thermal Sciences, 2011Co-Authors: Sateesh Gedupudi, T G Karayiannis, D B R Kenning, Yuying YanAbstract:Abstract Heat sinks using evaporation in arrays of parallel microchannels have potential for the removal of high heat fluxes from small areas. They suffer from flow instabilities and uneven distribution between channels that may cause local dryout and overheating. The current state of the art is reviewed critically. A simple 1-D model for Bubble Growth in a single channel with a compressible volume in its upstream plenum is developed as a tool for the rational design of measures known to reduce flow instabilities, namely inlet resistance and enhanced nucleation in every channel. The model considers two stages of partially and fully confined Bubble Growth in a single channel of rectangular cross-section, suggested by experimental observations, followed by venting of vapour to the downstream plenum. The experiments also show the influence of apparently minor changes in rig design and operation on upstream compressibility and flow reversal. The model considers upstream compressibility due to subcooled boiling in a preheater or trapped non-condensable gas and the reduction of flow reversal by inlet resistance. The feasibility of measuring transient axial variations in pressure within small channels using inexpensive transducers is demonstrated.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part ii approximate 3 d numerical simulation
International Journal of Thermal Sciences, 2011Co-Authors: Yuying Yan, Sateesh Gedupudi, T G Karayiannis, D B R KenningAbstract:Abstract This Part II of the paper reports the three-dimensional (3-D) numerical modelling on bubbly flow in confined mini-/micro-channels using the volume of fluid (VOF) method in commercial CFD code FLUENT. The numerical simulation aims to provide detailed information of the fields of velocity, temperature and pressure so as to further understand the effect of Bubble Growth on the flow field and heat transfer from the channel wall. In Part I, the experiment of flow boiling in a mini-/micro-channel of rectangular cross-section was carried out and a simple one-dimensional (1-D) model for the interaction of the pressure fluctuations during the Growth of a confined Bubble with various kinds of upstream compressibility was developed as an aid to the rational specification of inlet resistance. In Part II, the experimental observers and the theoretical model developed in Part I are tested by performing the 3-D numerical simulation of Bubble Growth from nucleation to full confinement. The simulation involves some approximations based on a concept of pseudo-boiling to avoid the well-known difficulties of modelling Bubble generation and Growth. During the simulation, the volumetric Growth rate of the Bubble is defined to match the experimental observations. At small times prior to Bubble detachment, a vapour flow was injected through a small hole in the wall to simulate nucleation. Following partial confinement, vapour injection was stopped and Growth was driven by the generation of vapour at a defined rate at the contact area between the Bubble and the superheated wall. The 3-D simulation reproduces the experimental observations of the distorted profile of the Bubble and its trajectory during partially confined Growth and provides information about flow and heat transfer in the bulk liquid outside the thin film region. The 3-D and 1-D predictions of the development of axial pressure distributions during partially and fully confined Growth are in satisfactory agreement.
D B R Kenning - One of the best experts on this subject based on the ideXlab platform.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part i experiments and 1 d modelling
International Journal of Thermal Sciences, 2011Co-Authors: Sateesh Gedupudi, T G Karayiannis, D B R Kenning, Yuying YanAbstract:Abstract Heat sinks using evaporation in arrays of parallel microchannels have potential for the removal of high heat fluxes from small areas. They suffer from flow instabilities and uneven distribution between channels that may cause local dryout and overheating. The current state of the art is reviewed critically. A simple 1-D model for Bubble Growth in a single channel with a compressible volume in its upstream plenum is developed as a tool for the rational design of measures known to reduce flow instabilities, namely inlet resistance and enhanced nucleation in every channel. The model considers two stages of partially and fully confined Bubble Growth in a single channel of rectangular cross-section, suggested by experimental observations, followed by venting of vapour to the downstream plenum. The experiments also show the influence of apparently minor changes in rig design and operation on upstream compressibility and flow reversal. The model considers upstream compressibility due to subcooled boiling in a preheater or trapped non-condensable gas and the reduction of flow reversal by inlet resistance. The feasibility of measuring transient axial variations in pressure within small channels using inexpensive transducers is demonstrated.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part ii approximate 3 d numerical simulation
International Journal of Thermal Sciences, 2011Co-Authors: Yuying Yan, Sateesh Gedupudi, T G Karayiannis, D B R KenningAbstract:Abstract This Part II of the paper reports the three-dimensional (3-D) numerical modelling on bubbly flow in confined mini-/micro-channels using the volume of fluid (VOF) method in commercial CFD code FLUENT. The numerical simulation aims to provide detailed information of the fields of velocity, temperature and pressure so as to further understand the effect of Bubble Growth on the flow field and heat transfer from the channel wall. In Part I, the experiment of flow boiling in a mini-/micro-channel of rectangular cross-section was carried out and a simple one-dimensional (1-D) model for the interaction of the pressure fluctuations during the Growth of a confined Bubble with various kinds of upstream compressibility was developed as an aid to the rational specification of inlet resistance. In Part II, the experimental observers and the theoretical model developed in Part I are tested by performing the 3-D numerical simulation of Bubble Growth from nucleation to full confinement. The simulation involves some approximations based on a concept of pseudo-boiling to avoid the well-known difficulties of modelling Bubble generation and Growth. During the simulation, the volumetric Growth rate of the Bubble is defined to match the experimental observations. At small times prior to Bubble detachment, a vapour flow was injected through a small hole in the wall to simulate nucleation. Following partial confinement, vapour injection was stopped and Growth was driven by the generation of vapour at a defined rate at the contact area between the Bubble and the superheated wall. The 3-D simulation reproduces the experimental observations of the distorted profile of the Bubble and its trajectory during partially confined Growth and provides information about flow and heat transfer in the bulk liquid outside the thin film region. The 3-D and 1-D predictions of the development of axial pressure distributions during partially and fully confined Growth are in satisfactory agreement.
Lucas M Hale - One of the best experts on this subject based on the ideXlab platform.
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large scale atomistic simulations of helium 3 Bubble Growth in complex palladium alloys
Journal of Chemical Physics, 2016Co-Authors: Lucas M Hale, Jonathan A. Zimmerman, Bryan M. WongAbstract:Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material’s structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and Growth of helium-3 Bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium Bubble Growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how ...
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large scale atomistic simulations of helium 3 Bubble Growth in complex palladium alloys
Journal of Chemical Physics, 2016Co-Authors: Lucas M Hale, Jonathan A. Zimmerman, Bryan M. WongAbstract:Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material's structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and Growth of helium-3 Bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium Bubble Growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how and why our developed potentials either meet or confound these expectations.
Sateesh Gedupudi - One of the best experts on this subject based on the ideXlab platform.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part i experiments and 1 d modelling
International Journal of Thermal Sciences, 2011Co-Authors: Sateesh Gedupudi, T G Karayiannis, D B R Kenning, Yuying YanAbstract:Abstract Heat sinks using evaporation in arrays of parallel microchannels have potential for the removal of high heat fluxes from small areas. They suffer from flow instabilities and uneven distribution between channels that may cause local dryout and overheating. The current state of the art is reviewed critically. A simple 1-D model for Bubble Growth in a single channel with a compressible volume in its upstream plenum is developed as a tool for the rational design of measures known to reduce flow instabilities, namely inlet resistance and enhanced nucleation in every channel. The model considers two stages of partially and fully confined Bubble Growth in a single channel of rectangular cross-section, suggested by experimental observations, followed by venting of vapour to the downstream plenum. The experiments also show the influence of apparently minor changes in rig design and operation on upstream compressibility and flow reversal. The model considers upstream compressibility due to subcooled boiling in a preheater or trapped non-condensable gas and the reduction of flow reversal by inlet resistance. The feasibility of measuring transient axial variations in pressure within small channels using inexpensive transducers is demonstrated.
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confined Bubble Growth during flow boiling in a mini micro channel of rectangular cross section part ii approximate 3 d numerical simulation
International Journal of Thermal Sciences, 2011Co-Authors: Yuying Yan, Sateesh Gedupudi, T G Karayiannis, D B R KenningAbstract:Abstract This Part II of the paper reports the three-dimensional (3-D) numerical modelling on bubbly flow in confined mini-/micro-channels using the volume of fluid (VOF) method in commercial CFD code FLUENT. The numerical simulation aims to provide detailed information of the fields of velocity, temperature and pressure so as to further understand the effect of Bubble Growth on the flow field and heat transfer from the channel wall. In Part I, the experiment of flow boiling in a mini-/micro-channel of rectangular cross-section was carried out and a simple one-dimensional (1-D) model for the interaction of the pressure fluctuations during the Growth of a confined Bubble with various kinds of upstream compressibility was developed as an aid to the rational specification of inlet resistance. In Part II, the experimental observers and the theoretical model developed in Part I are tested by performing the 3-D numerical simulation of Bubble Growth from nucleation to full confinement. The simulation involves some approximations based on a concept of pseudo-boiling to avoid the well-known difficulties of modelling Bubble generation and Growth. During the simulation, the volumetric Growth rate of the Bubble is defined to match the experimental observations. At small times prior to Bubble detachment, a vapour flow was injected through a small hole in the wall to simulate nucleation. Following partial confinement, vapour injection was stopped and Growth was driven by the generation of vapour at a defined rate at the contact area between the Bubble and the superheated wall. The 3-D simulation reproduces the experimental observations of the distorted profile of the Bubble and its trajectory during partially confined Growth and provides information about flow and heat transfer in the bulk liquid outside the thin film region. The 3-D and 1-D predictions of the development of axial pressure distributions during partially and fully confined Growth are in satisfactory agreement.
