Daiki Matsunaga
Tohoku University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Daiki Matsunaga.
Physical Review E | 2015
Kohei Kyoya; Daiki Matsunaga; Yohsuke Imai; Toshihiro Omori; Takuji Ishikawa
Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.
Science and Technology of Advanced Materials | 2016
Shunichi Ishida; Yohsuke Imai; Yuki Ichikawa; Stephanie Nix; Daiki Matsunaga; Toshihiro Omori; Takuji Ishikawa
We developed a numerical model of the behavior of a red blood cell infected by Plasmodium falciparum malaria on a wall in shear flow. The fluid and solid mechanics of an infected red blood cell (Pf-IRBC) were coupled with the biochemical interaction of ligand-receptor bindings. We used the boundary element method for fluid mechanics, the finite element method for membrane mechanics, and the Monte Carlo method for ligand-receptor interactions. We simulated the behavior of a Pf-IRBC in shear flow, focusing on the effects of bond type. For slip bonds, the Pf-IRBC exhibited firm adhesion, tumbling motion, and tank-treading motion, depending on the applied shear rate. The behavior of catch bonds resembled that of slip bonds, except for a ‘catch’ state at high shear stress. When the reactive compliance decreased to a value in the order of nm, both the slip and catch bonds behaved like an ideal bond. Such bonds do not respond to the force applied to the bond, and the velocity is stabilized at a high shear rate. Finally, we compared the numerical results with previous experiments for A4- and ItG-infected cells. We found that the interaction between PfEMP1 and ICAM-1 could be a nearly ideal bond, with a dissociation rate ranging from to . Graphical Abstract
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science | 2016
Takuji Ishikawa; Tomoyuki Tanaka; Yohsuke Imai; Toshihiro Omori; Daiki Matsunaga
The membrane tension of some kinds of ciliates has been suggested to regulate upward and downward swimming velocities under gravity. Despite its biological importance, deformation and membrane tension of a ciliate have not been clarified fully. In this study, we numerically investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modelled as a capsule with a hyperelastic membrane enclosing a Newtonian fluid. Thrust forces due to the ciliary beat were modelled as torques distributed above the cell body. The effects of membrane elasticity, the aspect ratio of the cells reference shape, and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like a heart shape, when the capillary number was sufficiently large. Under the influence of gravity, the membrane tension at the anterior end decreased in the upward swimming while it increased in the downward swimming. Moreover, gravity-induced deformation caused the cells to move gravitationally downwards or upwards, which resulted in a positive or negative geotaxis-like behaviour with a physical origin. These results are important in understanding the physiology of a ciliates biological responses to mechanical stimuli.
Archive | 2018
Yohsuke Imai; Daiki Matsunaga
Understanding the behavior of capsules in flow and the rheology of capsule suspensions is of fundamental importance for diverse problems in nature and engineering. The particle Reynolds number of capsules is often small, and the flow field is given by the boundary integral formulation of the Stokes equations. The boundary element method (BEM) based on the boundary integral formulation is thus one of the most accurate methods for simulating capsules under Stokes flow regime. A high computational cost of BEM, however, has limited its application to relatively small scale problems. We have developed a graphics process unit (GPU) computing of BEM for capsules and biological cells in Stokes flow. We have investigated rheological properties of capsules, and those of capsule suspensions using the GPU-accelerated BEM. Here, we provide an overview of our recent studies, particularly focusing on the shear viscosity of dense suspensions of capsules in simple shear flow; an overshoot phenomenon of the capsule deformation in oscillating shear flow; and the sedimentation of red blood cells.
ASME 2012 Summer Bioengineering Conference, Parts A and B | 2012
Stephanie Nix; Yohsuke Imai; Daiki Matsunaga; Takuji Ishikawa; Takami Yamaguchi
Lateral migration of cells in the bloodstream is affected by the material properties of the constituent cells. In blood vessels, red blood cells migrate to the center of the vessel, leading to the formation of a cell-free layer near the vessel wall; on the other hand, less deformable cells such as white blood cells and platelets are more likely to be found near the blood vessel wall. [1]Copyright
Journal of Fluid Mechanics | 2015
Daiki Matsunaga; Yohsuke Imai; Takami Yamaguchi; Takuji Ishikawa
Physical Review E | 2014
Stephanie Nix; Yohsuke Imai; Daiki Matsunaga; Takami Yamaguchi; Takuji Ishikawa
Journal of Biomechanical Science and Engineering | 2014
Daiki Matsunaga; Yohsuke Imai; Toshihiro Omori; Takuji Ishikawa; Takami Yamaguchi
Journal of Fluid Mechanics | 2016
Daiki Matsunaga; Yohsuke Imai; Takami Yamaguchi; Takuji Ishikawa
Journal of Fluid Mechanics | 2016
Daiki Matsunaga; Yohsuke Imai; Christian Wagner; Takuji Ishikawa