2025-04-11 九州大学
<関連情報>
- https://www.kyushu-u.ac.jp/ja/researches/view/1223
- https://www.kyushu-u.ac.jp/f/61334/25_0411_01.pdf
- https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/inertial-focusing-of-spherical-capsule-in-pulsatile-channel-flows/332CFF8DDF5B3AAF95CF32CDD435AA7A
脈動チャネル流における球状カプセルの慣性集束 Inertial focusing of spherical capsule in pulsatile channel flows
Naoki Takeishi,Kenta Ishimoto,Naoto Yokoyama and Marco Edoardo Rosti
Journal of Fluid Mechanics Published:09 April 2025
DOI:https://doi.org/10.1017/jfm.2025.184
Abstract
We present numerical analysis of the lateral movement of a spherical capsule in the steady and pulsatile channel flow of a Newtonian fluid for a wide range of oscillatory frequencies. Each capsule membrane satisfying strain-hardening characteristics is simulated for different Reynolds numbers Re and capillary numbers Ca. Our numerical results showed that capsules with high Ca exhibit axial focusing at finite Re similarly to the inertialess case. We observe that the speed of the axial focusing can be substantially accelerated by making the driving pressure gradient oscillate in time. We also confirm the existence of an optimal frequency that maximises the speed of axial focusing, which remains the same found in the absence of inertia. For relatively low Ca, however, the capsule exhibits off-centre focusing, resulting in various equilibrium radial positions depending on Re. Our numerical results further clarify the existence of a specific Re for which the effect of the flow pulsation to the equilibrium radial position is maximum. The roles of channel size on the lateral movements of the capsule are also addressed. Throughout our analyses, we have quantified the radial position of the capsule in a tube based on an empirical expression. Given that the speed of inertial focusing can be controlled by the oscillatory frequency, the results obtained here can be used for label-free cell alignment/sorting/separation techniques, e.g. for circulating tumour cells in cancer patients or precious haematopoietic cells such as colony-forming cells.
