The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
M. Grae Worster - One of the best experts on this subject based on the ideXlab platform.
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Solidification of a Binary Alloy
Journal of Computational Physics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:A finite-element simulation of Binary Alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster (1986) for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid (de Vahl Davis 1983, Mayne et al. 2000, Wan et al. 2001), in a porous medium with a constant porosity (Lauriat & Prasad 1989, Ni et al. 1997) and in a mixed liquid-porous medium with a spatially variable porosity (Ni et al. 1997, Zabaras & Samanta 2004). Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars & Worster (2006). Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying Binary Alloy solidification
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Solidification of a Binary Alloy: finite-element, single-domain simulation and new benchmark solutions
Journal of Computational Physics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:A finite-element simulation of Binary Alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster (1986) for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid (de Vahl Davis 1983, Mayne et al. 2000, Wan et al. 2001), in a porous medium with a constant porosity (Lauriat & Prasad 1989, Ni et al. 1997) and in a mixed liquid-porous medium with a spatially variable porosity (Ni et al. 1997, Zabaras & Samanta 2004). Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars & Worster (2006). Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying Binary Alloy solidification.
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Interfacial conditions between a pure fluid and a porous medium: implications for Binary Alloy solidification
Journal of Fluid Mechanics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:The single-domain, Darcy-Brinkman model is applied to some analytically tractable flows through adjacent porous and pure-fluid domains and is compared systematically with the multiple-domain, Stokes-Darcy model. In particular, we focus on the interaction between flow and solidification within the mushy layer during Binary Alloy solidification in a corner flow and on the effects of the chosen mathematical description on the resulting macrosegregation patterns. Large-scale results provided by the multiple-domain formulation depend strongly on the microscopic interfacial conditions. No satisfactory agreement between the single- and multiple-domain approaches is obtained when using previously suggested conditions written directly at the interface between the liquid and the porous medium. Rather, we define a viscous transition zone inside the porous domain, where Stokes equation still applies, and we impose continuity of pressure and velocities across it. This new condition provides good agreement between the two formulations of solidification problems when there is a continuous variation of porosity across the interface between a partially solidified region (mushy zone) and the melt.
Michael Le Bars - One of the best experts on this subject based on the ideXlab platform.
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Solidification of a Binary Alloy
Journal of Computational Physics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:A finite-element simulation of Binary Alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster (1986) for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid (de Vahl Davis 1983, Mayne et al. 2000, Wan et al. 2001), in a porous medium with a constant porosity (Lauriat & Prasad 1989, Ni et al. 1997) and in a mixed liquid-porous medium with a spatially variable porosity (Ni et al. 1997, Zabaras & Samanta 2004). Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars & Worster (2006). Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying Binary Alloy solidification
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Solidification of a Binary Alloy: finite-element, single-domain simulation and new benchmark solutions
Journal of Computational Physics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:A finite-element simulation of Binary Alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster (1986) for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid (de Vahl Davis 1983, Mayne et al. 2000, Wan et al. 2001), in a porous medium with a constant porosity (Lauriat & Prasad 1989, Ni et al. 1997) and in a mixed liquid-porous medium with a spatially variable porosity (Ni et al. 1997, Zabaras & Samanta 2004). Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars & Worster (2006). Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying Binary Alloy solidification.
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Interfacial conditions between a pure fluid and a porous medium: implications for Binary Alloy solidification
Journal of Fluid Mechanics, 2006Co-Authors: Michael Le Bars, M. Grae WorsterAbstract:The single-domain, Darcy-Brinkman model is applied to some analytically tractable flows through adjacent porous and pure-fluid domains and is compared systematically with the multiple-domain, Stokes-Darcy model. In particular, we focus on the interaction between flow and solidification within the mushy layer during Binary Alloy solidification in a corner flow and on the effects of the chosen mathematical description on the resulting macrosegregation patterns. Large-scale results provided by the multiple-domain formulation depend strongly on the microscopic interfacial conditions. No satisfactory agreement between the single- and multiple-domain approaches is obtained when using previously suggested conditions written directly at the interface between the liquid and the porous medium. Rather, we define a viscous transition zone inside the porous domain, where Stokes equation still applies, and we impose continuity of pressure and velocities across it. This new condition provides good agreement between the two formulations of solidification problems when there is a continuous variation of porosity across the interface between a partially solidified region (mushy zone) and the melt.
Changhee Lee - One of the best experts on this subject based on the ideXlab platform.
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characteristics and heat treatment of cold sprayed al sn Binary Alloy coatings
Applied Surface Science, 2009Co-Authors: Xian Jin Ning, Hyungjun Kim, Jinhong Kim, Changhee LeeAbstract:Abstract In this study, Al–Sn Binary Alloy coatings were prepared with Al–5 wt.% Sn (Al–5Sn) and Al–10 wt.% Sn (Al–10Sn) gas atomized powders by low pressure and high pressure cold spray process. The microstructure and microhardness of the coatings were characterized. To understand the coarsening of tin in the coating, the as-sprayed coatings were annealed at 150, 200, 250 and 300 °C for 1 h, respectively. The effect of annealing on microstructure and the bond strength of the coatings were investigated. The results show that Al–5Sn coating can be deposited by high pressure cold spray with nitrogen while Al–10Sn can only be deposited by low pressure cold spray with helium gas. Both Al–5Sn and Al–10Sn coatings present dense structures. The fraction of Sn in as-sprayed coatings is consistent with that in feed stock powders. The coarsening and/or migration of Sn phase in the coatings were observed when the annealing temperature exceeds 200 °C. Furthermore, the microhardness of the coatings decreased significantly at the annealing temperature of 250 °C. EDXA analysis shows that the heat treatment has no significant effect on fraction of Sn phase in Al–5Sn coatings. Bonding strength of as-sprayed Al–10Sn coating is slightly higher than that of Al–5Sn coating. Annealing at 200 °C can increase the bonding strength of Al–5Sn coatings.
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cold spraying of al sn Binary Alloy coating characteristics and particle bonding features
Surface & Coatings Technology, 2008Co-Authors: Xian Jin Ning, Jaehoon Jang, Hyungjun Kim, Changhee LeeAbstract:Abstract In this study, Al–Sn Binary Alloy coatings were prepared with Al–10 wt.% Sn (Al–10Sn) and Al–20 wt.%Sn (Al–20Sn) gas atomized Alloy powders by low pressure cold spray process. The microstructure and microhardness of the coatings were characterized. The deposition efficiency of Al–Sn and pure aluminum powder were tested on sand blasted substrates of Al6061, copper and SUS304. To investigate the particle bonding features of Al–10Sn powder, the wipe test was carried out on polished substrate surfaces. The average critical velocity of Al–Sn Alloy powders was estimated combining with the deposition efficiency. The results proved that Al–Sn coatings with dense and uniform structure can be deposited successfully by low pressure cold spray with helium as the propellant gas. The weight content of tin in Al–Sn coating is 12% and 22% for Al–10Sn and Al–20Sn coating, respectively. With the increase of tin content in feedstock powder, the as-sprayed coatings present similar microhardness of 73 and 74 for Al–10Sn and Al–20Sn while, on the other hand, the deposition efficiency decreased. Bonding features of Al–10Sn particles indicated that the melting of tin phase occurred on the contact interface during particle impacting. This melting of tin phase and low strength of tin may affect the particle bonding process and hence increase the critical velocity for Al–Sn Binary Alloy powders.
Grae M Worster - One of the best experts on this subject based on the ideXlab platform.
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interfacial conditions between a pure fluid and a porous medium implications for Binary Alloy solidification
Journal of Fluid Mechanics, 2006Co-Authors: Le M Bars, Grae M WorsterAbstract:The single-domain Darcy–Brinkman model is applied to some analytically tractable flows through adjacent porous and pure-fluid domains and is compared systematically with the multiple-domain Stokes–Darcy model. In particular, we focus on the interaction between flow and solidification within the mushy layer during Binary Alloy solidification in a corner flow and on the effects of the chosen mathematical description on the resulting macrosegregation patterns. Large-scale results provided by the multiple-domain formulation depend strongly on the microscopic interfacial conditions. No satisfactory agreement between the single- and multiple-domain approaches is obtained when using previously suggested conditions written directly at the interface between the liquid and the porous medium. Rather, we define a viscous transition zone inside the porous domain, where the Stokes equation still applies, and we impose continuity of pressure and velocities across it. This new condition provides good agreement between the two formulations of solidification problems when there is a continuous variation of porosity across the interface between a partially solidified region (mushy zone) and the melt.
Xian Jin Ning - One of the best experts on this subject based on the ideXlab platform.
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characteristics and heat treatment of cold sprayed al sn Binary Alloy coatings
Applied Surface Science, 2009Co-Authors: Xian Jin Ning, Hyungjun Kim, Jinhong Kim, Changhee LeeAbstract:Abstract In this study, Al–Sn Binary Alloy coatings were prepared with Al–5 wt.% Sn (Al–5Sn) and Al–10 wt.% Sn (Al–10Sn) gas atomized powders by low pressure and high pressure cold spray process. The microstructure and microhardness of the coatings were characterized. To understand the coarsening of tin in the coating, the as-sprayed coatings were annealed at 150, 200, 250 and 300 °C for 1 h, respectively. The effect of annealing on microstructure and the bond strength of the coatings were investigated. The results show that Al–5Sn coating can be deposited by high pressure cold spray with nitrogen while Al–10Sn can only be deposited by low pressure cold spray with helium gas. Both Al–5Sn and Al–10Sn coatings present dense structures. The fraction of Sn in as-sprayed coatings is consistent with that in feed stock powders. The coarsening and/or migration of Sn phase in the coatings were observed when the annealing temperature exceeds 200 °C. Furthermore, the microhardness of the coatings decreased significantly at the annealing temperature of 250 °C. EDXA analysis shows that the heat treatment has no significant effect on fraction of Sn phase in Al–5Sn coatings. Bonding strength of as-sprayed Al–10Sn coating is slightly higher than that of Al–5Sn coating. Annealing at 200 °C can increase the bonding strength of Al–5Sn coatings.
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cold spraying of al sn Binary Alloy coating characteristics and particle bonding features
Surface & Coatings Technology, 2008Co-Authors: Xian Jin Ning, Jaehoon Jang, Hyungjun Kim, Changhee LeeAbstract:Abstract In this study, Al–Sn Binary Alloy coatings were prepared with Al–10 wt.% Sn (Al–10Sn) and Al–20 wt.%Sn (Al–20Sn) gas atomized Alloy powders by low pressure cold spray process. The microstructure and microhardness of the coatings were characterized. The deposition efficiency of Al–Sn and pure aluminum powder were tested on sand blasted substrates of Al6061, copper and SUS304. To investigate the particle bonding features of Al–10Sn powder, the wipe test was carried out on polished substrate surfaces. The average critical velocity of Al–Sn Alloy powders was estimated combining with the deposition efficiency. The results proved that Al–Sn coatings with dense and uniform structure can be deposited successfully by low pressure cold spray with helium as the propellant gas. The weight content of tin in Al–Sn coating is 12% and 22% for Al–10Sn and Al–20Sn coating, respectively. With the increase of tin content in feedstock powder, the as-sprayed coatings present similar microhardness of 73 and 74 for Al–10Sn and Al–20Sn while, on the other hand, the deposition efficiency decreased. Bonding features of Al–10Sn particles indicated that the melting of tin phase occurred on the contact interface during particle impacting. This melting of tin phase and low strength of tin may affect the particle bonding process and hence increase the critical velocity for Al–Sn Binary Alloy powders.