The Experts below are selected from a list of 72123 Experts worldwide ranked by ideXlab platform
Takashi Matsuoka - One of the best experts on this subject based on the ideXlab platform.
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Unstable Mixing Region in wurtzite In1−X−YGaXAlYN
Journal of Crystal Growth, 1998Co-Authors: Takashi MatsuokaAbstract:In In 1-X Ga X N epitaxially grown by MOVPE, phase separation is experimentally found to occur at an indium composition of more than 20% from X-ray diffraction and microscopic examination using an analytical electron transmission microscope. Fitting the spinodal isotherms calculated from the free energy of Mixing based on a strictly regular solution approximation using delta-lattice-parameter method to the experimental data, the constant of proportionality K between a lattice constant and the pseudobinary interaction parameter is determined. Using this K value, the pseudobinary interaction parameter is calculated using the delta-lattice-parameter method, and the unstable Mixing Region in a wurtzite structure In 1-X-Y Ga X Al Y N quaternary system is predicted. © 1998 Elsevier Science B.V. All rights reserved.
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unstable Mixing Region in wurtzite in1 x ygaxalyn
Journal of Crystal Growth, 1998Co-Authors: Takashi MatsuokaAbstract:In In 1-X Ga X N epitaxially grown by MOVPE, phase separation is experimentally found to occur at an indium composition of more than 20% from X-ray diffraction and microscopic examination using an analytical electron transmission microscope. Fitting the spinodal isotherms calculated from the free energy of Mixing based on a strictly regular solution approximation using delta-lattice-parameter method to the experimental data, the constant of proportionality K between a lattice constant and the pseudobinary interaction parameter is determined. Using this K value, the pseudobinary interaction parameter is calculated using the delta-lattice-parameter method, and the unstable Mixing Region in a wurtzite structure In 1-X-Y Ga X Al Y N quaternary system is predicted. © 1998 Elsevier Science B.V. All rights reserved.
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Calculation of unstable Mixing Region in wurtzite In1−x−yGaxAlyN
Applied Physics Letters, 1997Co-Authors: Takashi MatsuokaAbstract:The wurtzite structure In1−x−yGaxAlyN quaternary system with a wide band gap, which is useful for light emitters in the wavelength Region shorter than green, is studied with respect to the unstable Region in Mixing. This unstable Region in Mixing is calculated from the free energy of Mixing using the strictly regular solution model. The interaction parameter used in this calculation is obtained using the delta-lattice-parameter method. From this calculation, the ternary alloys of InAlN, InGaN, and GaAlN are, respectively, predicted to always, sometimes, and hardly ever have a unstable Mixing Region at the temperature lower than 3000 °C.
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calculation of unstable Mixing Region in wurtzite in1 x ygaxalyn
Applied Physics Letters, 1997Co-Authors: Takashi MatsuokaAbstract:The wurtzite structure In1−x−yGaxAlyN quaternary system with a wide band gap, which is useful for light emitters in the wavelength Region shorter than green, is studied with respect to the unstable Region in Mixing. This unstable Region in Mixing is calculated from the free energy of Mixing using the strictly regular solution model. The interaction parameter used in this calculation is obtained using the delta-lattice-parameter method. From this calculation, the ternary alloys of InAlN, InGaN, and GaAlN are, respectively, predicted to always, sometimes, and hardly ever have a unstable Mixing Region at the temperature lower than 3000 °C.
Stéphane Roux - One of the best experts on this subject based on the ideXlab platform.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the side walls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics of a blob of dye in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the sidewalls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
Emmanuelle Gouillart - One of the best experts on this subject based on the ideXlab platform.
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Moving walls accelerate Mixing
2011Co-Authors: Jean-luc Thiffeault, Emmanuelle Gouillart, Olivier DauchotAbstract:Mixing in viscous fluids is challenging, but chaotic advection in principle allows efficient Mixing. In the best possible scenario, the decay rate of the concentration profile of a passive scalar should be exponential in time. In practice, several authors have found that the no-slip boundary condition at the walls of a vessel can slow down Mixing considerably, turning an exponential decay into a power law. This slowdown affects the whole Mixing Region, and not just the vicinity of the wall. The reason is that when the chaotic Mixing Region extends to the wall, a separatrix connects to it. The approach to the wall along that separatrix is polynomial in time and dominates the long-time decay. However, if the walls are moved or rotated, closed orbits appear, separated from the central Mixing Region by a hyperbolic fixed point with a homoclinic orbit. The long-time approach to the fixed point is exponential, so an overall exponential decay is recovered, albeit with a thin unmixed Region near the wall.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the side walls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics of a blob of dye in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the sidewalls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
Olivier Dauchot - One of the best experts on this subject based on the ideXlab platform.
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Moving walls accelerate Mixing
2011Co-Authors: Jean-luc Thiffeault, Emmanuelle Gouillart, Olivier DauchotAbstract:Mixing in viscous fluids is challenging, but chaotic advection in principle allows efficient Mixing. In the best possible scenario, the decay rate of the concentration profile of a passive scalar should be exponential in time. In practice, several authors have found that the no-slip boundary condition at the walls of a vessel can slow down Mixing considerably, turning an exponential decay into a power law. This slowdown affects the whole Mixing Region, and not just the vicinity of the wall. The reason is that when the chaotic Mixing Region extends to the wall, a separatrix connects to it. The approach to the wall along that separatrix is polynomial in time and dominates the long-time decay. However, if the walls are moved or rotated, closed orbits appear, separated from the central Mixing Region by a hyperbolic fixed point with a homoclinic orbit. The long-time approach to the fixed point is exponential, so an overall exponential decay is recovered, albeit with a thin unmixed Region near the wall.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the side walls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics of a blob of dye in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the sidewalls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
Jean-luc Thiffeault - One of the best experts on this subject based on the ideXlab platform.
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Moving walls accelerate Mixing
2011Co-Authors: Jean-luc Thiffeault, Emmanuelle Gouillart, Olivier DauchotAbstract:Mixing in viscous fluids is challenging, but chaotic advection in principle allows efficient Mixing. In the best possible scenario, the decay rate of the concentration profile of a passive scalar should be exponential in time. In practice, several authors have found that the no-slip boundary condition at the walls of a vessel can slow down Mixing considerably, turning an exponential decay into a power law. This slowdown affects the whole Mixing Region, and not just the vicinity of the wall. The reason is that when the chaotic Mixing Region extends to the wall, a separatrix connects to it. The approach to the wall along that separatrix is polynomial in time and dominates the long-time decay. However, if the walls are moved or rotated, closed orbits appear, separated from the central Mixing Region by a hyperbolic fixed point with a homoclinic orbit. The long-time approach to the fixed point is exponential, so an overall exponential decay is recovered, albeit with a thin unmixed Region near the wall.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the side walls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.
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Open-flow Mixing: Experimental evidence for strange eigenmodes
Physics of Fluids, 2009Co-Authors: Emmanuelle Gouillart, Jean-luc Thiffeault, Olivier Dauchot, Stéphane RouxAbstract:We investigate experimentally the Mixing dynamics of a blob of dye in a channel flow with a finite stirring Region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their Mixing Region. In the first case, the Mixing Region is separated from the sidewalls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the Mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the Mixing Region leads to non-self-similar Mixing dynamics.