Fluctuating diffusivity emerges even in binary gas mixtures

Nakai, Fumiaki; Masubuchi, Yuichi; Doi, Yuya; Ishida, Takuo; Uneyama, Takashi

doi:10.1103/physreve.107.014605

Cited by 7 publications

(12 citation statements)

References 36 publications

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“…To characterize non-Gaussian diffusion, the non-Gaussian parameter α is often employed [91,92,93] and defined in three-dimensional systems as [94]…”

Section: Application Of 2sfd Model To Gas O 2 In Cement Pastementioning

confidence: 99%

Gas Diffusion in Cement Pastes: An Analysis using a Fluctuating Diffusivity Model

Nakai¹,

Ishida²

2023

Preprint

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This work propose an application of the concept of fluctuating diffusivity to the diffusion of gas molecules in cementitious materials, particularly through a two-state fluctuating diffusivity (2SFD) model. The 2SFD model is utilized to investigate the diffusion of oxygen in cement pastes. The analysis provides a reasonable description of the diffusion coefficient of oxygen in cement pastes, and highlights the presence of non-Gaussian diffusion, which can be attributed to the heterogeneous microstructure. The presence of non-Gaussianity in the probability density of the molecule's displacement, characterized by heavier tails than those of the Gaussian distribution, may have a significant impact on the durability assessments of concrete structures.

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“…To characterize non-Gaussian diffusion, the non-Gaussian parameter α is often employed [91,92,93] and defined in three-dimensional systems as [94]…”

Section: Application Of 2sfd Model To Gas O 2 In Cement Pastementioning

confidence: 99%

Gas Diffusion in Cement Pastes: An Analysis using a Fluctuating Diffusivity Model

Nakai¹,

Ishida²

2023

Preprint

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“…In the current case, the collision frequency density f (u) for a collision with a direction vector u thoroughly characterizes the collision statistics. f (u) is obtained from the collision statistics for the binary gas mixture [3,5] by setting the surrounding gas velocity to be 0:…”

Section: A Lorentz Gasmentioning

confidence: 99%

“…In contrast to these complex systems, there is no heterogeneity nor internal degrees of freedom in the gas mixture. In the previous work [5], the origin of the non-Gaussian behavior was attributed to the fluctuating diffusivity which arises from a timescale separation between the velocity direction and speed of the minor light particle.…”

Section: Introductionmentioning

confidence: 99%

“…Gas diffusion is a classical problem [1][2][3][4], and it may be considered to be fully understood nowadays. However, recent work revealed that gas diffusion is not that simple nor fully understood [5]. The authors [5] numerically investigated the diffusion of a light gas particle in gas mixtures with mass and fraction contrast and found that the minor light molecule exhibits Brownin yet non-Gaussian diffusion: the mean square displacement (MSD) is linear in time, while the displacement distribution deviates from the Gaussian distribution.…”

Section: Introductionmentioning

confidence: 99%

“…However, recent work revealed that gas diffusion is not that simple nor fully understood [5]. The authors [5] numerically investigated the diffusion of a light gas particle in gas mixtures with mass and fraction contrast and found that the minor light molecule exhibits Brownin yet non-Gaussian diffusion: the mean square displacement (MSD) is linear in time, while the displacement distribution deviates from the Gaussian distribution. The Brownian yet non-Gaussian diffusion has been widely observed in complex systems with heterogeneous environments and/or conformational degrees of freedom, such as glass-forming liquids [6], polymeric fluids [7,8], colloidal suspensions [9,10], biological systems [11][12][13], and active matters [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Brownian yet non-Gaussian diffusion of a light particle in heavy gas: Lorentz gas based analysis

Nakai¹,

Uneyama²

2023

Preprint

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Non-Gaussian diffusion was recently observed in a gas mixture with mass and fraction contrast [F. Nakai et al, Phys. Rev. E 107, 014605 (2023)]. The mean square displacement of a minor gas particle with a small mass is linear in time, while the displacement distribution deviates from the Gaussian distribution, which is called the Brownian yet non-Gaussian diffusion. In this work, we theoretically analyze this case where the mass contrast is sufficiently large. Major heavy particles can be interpreted as immobile obstacles, and a minor light particle behaves like a Lorentz gas particle within an intermediate time scale. Despite the similarity between the gas mixture and the conventional Lorentz gas system, the Lorentz gas description cannot fully describe the Brownian yet non-Gaussian diffusion. A successful description can be achieved through an ensemble average of the statistical quantities of the Lorentz gas over the initial speed.

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Gas diffusion in cement pastes: An analysis using a fluctuating diffusivity model

Nakai,

Ishida

2023

Construction and Building Materials

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Fluctuating diffusivity emerges even in binary gas mixtures

Cited by 7 publications

References 36 publications

Gas Diffusion in Cement Pastes: An Analysis using a Fluctuating Diffusivity Model

Gas Diffusion in Cement Pastes: An Analysis using a Fluctuating Diffusivity Model

Brownian yet non-Gaussian diffusion of a light particle in heavy gas: Lorentz gas based analysis

Gas diffusion in cement pastes: An analysis using a fluctuating diffusivity model

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