Rei Kurita - Academia.edu (original) (raw)
Papers by Rei Kurita
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2007
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2008
Journal of Physics: Condensed Matter, 2021
Two-dimensional convection rolls are usually stable near the critical Rayleigh number in single c... more Two-dimensional convection rolls are usually stable near the critical Rayleigh number in single component fluids. However, in binary mixtures, it has been reported that the roll patterns become unstable over time and that stagnant domains are transiently formed. The formation of transient stagnant domains (TSD) occurs in systems where one component is more viscous than the other. Meanwhile, the mechanism of the TSD formation has been unclear yet. Here, we use experiments using well-mixed silicone oils and colloidal suspensions to show that the formation of transient stagnant regions is chiefly related to the concentration dependence of the kinematic viscosity rather than spatially averaged properties. Furthermore, we find that the concentration dependence of density is also related to the formation of stagnant regions. The coupling between density, viscosity and concentration fluctuations may play an important role for thermal convection in multi-component mixtures.
Soft Matter
Fluorescence micrograph of the active holes created in a droplet of an ionic liquid.
Often experimentalists study particulate samples that are nominally monodisperse. In reality many... more Often experimentalists study particulate samples that are nominally monodisperse. In reality many samples have a polydispersity of 4-10%. At the level of an individual particle, the consequences of this polydispersity are unknown as it is difficult to measure an individual particle size from images of a dense sample. We propose a method to estimate individual particle radii from threedimensional data of the particle positions. We validate our method by numerical simulations of four major systems: random close packing, colloidal gels, nominally monodisperse dense samples, and nominally binary dense samples. We then apply our method to experimental data from moderately concentrated colloidal suspensions observed with confocal microscopy. We demonstrate that we can recover the full particle size distribution in situ. Lastly, we use our method to study the relationship between homogeneous colloidal crystal nucleation and particle sizes. We show that nucleation occurs in regions that are...
The dissolution dynamics of ionic liquid (IL) in ILs/water systems and at an IL/water/air interfa... more The dissolution dynamics of ionic liquid (IL) in ILs/water systems and at an IL/water/air interface is investigated. When a hydrophobic IL dissolves in water, it forms a droplet with a clear interface even though it is soluble to water. The transition between the two liquids remains sharp throughout the dissolution process, and it seems that the diffusion occurs unidirectionally, only outward from the droplet. The dissolution dynamics can be described as an activation process in which IL molecules escape from the droplet with a probability proportional to the surface area of the droplet. This distinctive feature of the dissolution dynamics may relate to alignment of the IL molecules at the IL/water interface. On the other hand, an active motion of water appears around the IL droplet, when hydrophobic ILs dissolve in a thin layer of water with contacting the air/water boundary .
Bulletin of the American Physical Society, 2012
ABSTRACT We have developed a technique to estimate the radius of every particle observed in a con... more ABSTRACT We have developed a technique to estimate the radius of every particle observed in a confocal microscopy experiment. From simulations, we verify that the particle radii are estimated to high accuracy in a variety of samples: dense colloidal suspensions, colloidal gels, and binary samples. This method allows us to determine in situ the particle size distribution. Furthermore, this method lets us find relationships between individual particle size and dynamical behaviors. First, crystal nucleation occurs in regions that are locally more monodisperse. Second, in dense samples, particle mobility is well correlated with the local volume fraction, defined as the true particle volume divided by the particle's Voronoi volume.
Soft Matter
Collapse of liquid films in a foam is characteristic compared to that of individual films. The me... more Collapse of liquid films in a foam is characteristic compared to that of individual films. The mechanism and physical conditions of collective bubble collapse which directly contribute to foam stability have been clarified.
JAPANESE JOURNAL OF MULTIPHASE FLOW
Gravitational instability, which is a typical example of hydrodynamic instabilities, occurs due t... more Gravitational instability, which is a typical example of hydrodynamic instabilities, occurs due to density difference. When a heavy fluid lies over a light fluid in a constant gravitational field, fluctuations at the interface gradually increase and then macroscopic flows occur. The gravitational instability can be found not only in liquid-liquid interface but also in the gravitational settling of granular materials. However, the gravitational instability of liquid systems and granular systems have been discussed individually in most cases. We quantitatively find a close relationship of the gravitational instability between the physical gel and granular systems. We also find that those behaviors are determined by the thickness of the fluidization region.
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2007
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan, 2017
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2008
Journal of Physics: Condensed Matter, 2021
Two-dimensional convection rolls are usually stable near the critical Rayleigh number in single c... more Two-dimensional convection rolls are usually stable near the critical Rayleigh number in single component fluids. However, in binary mixtures, it has been reported that the roll patterns become unstable over time and that stagnant domains are transiently formed. The formation of transient stagnant domains (TSD) occurs in systems where one component is more viscous than the other. Meanwhile, the mechanism of the TSD formation has been unclear yet. Here, we use experiments using well-mixed silicone oils and colloidal suspensions to show that the formation of transient stagnant regions is chiefly related to the concentration dependence of the kinematic viscosity rather than spatially averaged properties. Furthermore, we find that the concentration dependence of density is also related to the formation of stagnant regions. The coupling between density, viscosity and concentration fluctuations may play an important role for thermal convection in multi-component mixtures.
Soft Matter
Fluorescence micrograph of the active holes created in a droplet of an ionic liquid.
Often experimentalists study particulate samples that are nominally monodisperse. In reality many... more Often experimentalists study particulate samples that are nominally monodisperse. In reality many samples have a polydispersity of 4-10%. At the level of an individual particle, the consequences of this polydispersity are unknown as it is difficult to measure an individual particle size from images of a dense sample. We propose a method to estimate individual particle radii from threedimensional data of the particle positions. We validate our method by numerical simulations of four major systems: random close packing, colloidal gels, nominally monodisperse dense samples, and nominally binary dense samples. We then apply our method to experimental data from moderately concentrated colloidal suspensions observed with confocal microscopy. We demonstrate that we can recover the full particle size distribution in situ. Lastly, we use our method to study the relationship between homogeneous colloidal crystal nucleation and particle sizes. We show that nucleation occurs in regions that are...
The dissolution dynamics of ionic liquid (IL) in ILs/water systems and at an IL/water/air interfa... more The dissolution dynamics of ionic liquid (IL) in ILs/water systems and at an IL/water/air interface is investigated. When a hydrophobic IL dissolves in water, it forms a droplet with a clear interface even though it is soluble to water. The transition between the two liquids remains sharp throughout the dissolution process, and it seems that the diffusion occurs unidirectionally, only outward from the droplet. The dissolution dynamics can be described as an activation process in which IL molecules escape from the droplet with a probability proportional to the surface area of the droplet. This distinctive feature of the dissolution dynamics may relate to alignment of the IL molecules at the IL/water interface. On the other hand, an active motion of water appears around the IL droplet, when hydrophobic ILs dissolve in a thin layer of water with contacting the air/water boundary .
Bulletin of the American Physical Society, 2012
ABSTRACT We have developed a technique to estimate the radius of every particle observed in a con... more ABSTRACT We have developed a technique to estimate the radius of every particle observed in a confocal microscopy experiment. From simulations, we verify that the particle radii are estimated to high accuracy in a variety of samples: dense colloidal suspensions, colloidal gels, and binary samples. This method allows us to determine in situ the particle size distribution. Furthermore, this method lets us find relationships between individual particle size and dynamical behaviors. First, crystal nucleation occurs in regions that are locally more monodisperse. Second, in dense samples, particle mobility is well correlated with the local volume fraction, defined as the true particle volume divided by the particle's Voronoi volume.
Soft Matter
Collapse of liquid films in a foam is characteristic compared to that of individual films. The me... more Collapse of liquid films in a foam is characteristic compared to that of individual films. The mechanism and physical conditions of collective bubble collapse which directly contribute to foam stability have been clarified.
JAPANESE JOURNAL OF MULTIPHASE FLOW
Gravitational instability, which is a typical example of hydrodynamic instabilities, occurs due t... more Gravitational instability, which is a typical example of hydrodynamic instabilities, occurs due to density difference. When a heavy fluid lies over a light fluid in a constant gravitational field, fluctuations at the interface gradually increase and then macroscopic flows occur. The gravitational instability can be found not only in liquid-liquid interface but also in the gravitational settling of granular materials. However, the gravitational instability of liquid systems and granular systems have been discussed individually in most cases. We quantitatively find a close relationship of the gravitational instability between the physical gel and granular systems. We also find that those behaviors are determined by the thickness of the fluidization region.