Drag coefficient of a rigid spherical particle in a near-critical binary fluid mixture, beyond the regime of the Gaussian model

  • Event Date: 2024-07-12 Fri 10:30 ~ 12:30
  • Complex Systems
  • Speaker: Dr. Shunsuke Yabunaka (Japan Atomic Energy Agency)  /  Host: prof. Hsuan-Yi Chen
    Place: R307, Cosmology Hall, NTU

Title: Drag coefficient of a rigid spherical particle in a near-critical binary fluid mixture, beyond the regime of the Gaussian model
Speaker: Dr. Shunsuke Yabunaka (Japan Atomic Energy Agency)
Time: 2024/07/12 (Fri.) 10:30 a.m - 12:30 p.m
Place: R307, Cosmology Hall, NTU

Abstract
The drag coefficient of a rigid spherical particle, immersed in a near critical binary mixture, deviates from Stokes law due to the preferential adsorption on the particle surface. The deviation is experimentally shown to depend approximately linearly on the bulk correlation length of the composition fluctuation far from the particle [1]. Previous studies with Gaussian free-energy density, where the correlation length is uniform, yield much steeper dependence the linear one [2]. We show that the dependence becomes gradual and close to the linear one when the spatial inhomogeneity is taken into account in the free-energy density [3].  We also discuss recent improvement of numerics, which enables calculation with much larger bulk correlation lengths and may be useful for other hydrodynamic problems in soft matter physics.

[1] A. R. Omari et al, Phys. Rev. Lett. 103, 225705 (2009).
[2] R. Okamoto, Y. Fujitani and S. Komura, J. Phys. Soc. Jpn 82, 084003 (2013).
[3] S. Yabunaka and Y. Fujitani, Journal of Fluid Mechanics, Volume 886, A2 (2020)

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