Diffusion enhancement induced by hydrodynamic flowProf. Hiroyuki Kitahata (Graduate School of Science, Chiba University)

Reciprocal flow seems to be unable to transport the solutes in time average but it can enhance the diffusion of the solute. We focus on the diffusion process coupled with the reciprocal flow. We theoretically derive that the diffusion process can be enhanced by the reciprocal flow, and the results are confirmed via numerical calculation of the over-damped Langevin equation with a reciprocal flow. This diffusion enhancement corresponds to the experimental results on the diffusion enhancement in an oscillating levitated droplet [1]. Moreover, diffusion enhancement was reported in the living cell, in which active proteins change their form and induce the flow. Such diffusion enhancement is also discussed by considering the stochastic change in the configuration of the active cell and the induced hydrodynamic flow around them [2]. [1] Koyano, Kitahata, Hasegawa, Matsumoto, Nishinari, Watanabe, Kaneko, Abe, Phys. Rev. E 102 033109 (2020). [2] Mikhailov, Koyano, Kitahata, J. Phys. Soc. Jpn. 86, 101013 (2017).