The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Takami Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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rheology of a dense suspension of spherical capsules under Simple Shear Flow
Journal of Fluid Mechanics, 2016Co-Authors: Daiki Matsunaga, Takami Yamaguchi, Yohsuke Imai, Takuji IshikawaAbstract:We present a numerical analysis of the rheology of a dense suspension of spherical capsules in Simple Shear Flow in the Stokes Flow regime. The behaviour of neo-Hookean capsules is simulated for a volume fraction up to ${\it\phi}=0.4$ by graphics processing unit computing based on the boundary element method with a multipole expansion. To describe the specific viscosity using a polynomial equation of the volume fraction, the coefficients of the equation are calculated by least-squares fitting. The results suggest that the effect of higher-order terms is much smaller for capsule suspensions than rigid sphere suspensions; for example, $O({\it\phi}^{3})$ terms account for only 8 % of the specific viscosity even at ${\it\phi}=0.4$ for capillary numbers $Ca\geqslant 0.1$ . We also investigate the relationship between the deformation and orientation of the capsules and the suspension rheology. When the volume fraction increases, the deformation of the capsules increases while the orientation angle of the capsules with respect to the Flow direction decreases. Therefore, both the specific viscosity and the normal stress difference increase with volume fraction due to the increased deformation, whereas the decreased orientation angle suppresses the specific viscosity, but amplifies the normal stress difference.
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membrane tension of red blood cells pairwisely interacting in Simple Shear Flow
Journal of Biomechanics, 2013Co-Authors: Toshihiro Omori, Takuji Ishikawa, Yohsuke Imai, Takami YamaguchiAbstract:Flow-induced membrane tension contributes to the release of molecules by red blood cells (RBCs), and extremely high tension may cause haemolysis. Here, we investigated the membrane tension of RBCs during pairwise interactions in Simple Shear Flow, given that pairwise interactions form the basis of many-body interactions. RBCs were modelled as capsules with a two-dimensional hyperelastic membrane, and large deformations were solved by the finite element method. Due to the small size of the RBCs, surrounding fluid motion was estimated as a Stokes Flow and solved by the boundary element method. The results showed that the maximum isotropic tension appeared around the dimple of the biconcave surface and not around the rim. A comparison of the results with solitary cases indicated that the maximum principal tension and isotropic tension were significantly increased by cell–cell interaction effects. As the volume fraction of RBCs is large under physiological conditions, as well as in blood Flow in vitro, cell–cell interactions must be analysed carefully when considering mechanotransduction and haemolysis in blood Flow.
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tension of red blood cell membrane in Simple Shear Flow
Physical Review E, 2012Co-Authors: Toshihiro Omori, Dominique Barthesbiesel, Takuji Ishikawa, Yohsuke Imai, Annevirginie Salsac, Takami YamaguchiAbstract:When a red blood cell (RBC) is subjected to an external Flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a Simple Shear Flow and the resulting elastic tensions on the membrane. The large deformation of the red blood cell is modelled by coupling a finite element method to solve the membrane mechanics and a boundary element method to solve the Flows of the internal and external liquids. Depending on the capillary number Ca, ratio of the viscous to elastic forces, we observe three kinds of RBC motion: tumbling at low Ca, swinging at larger Ca, and breathing at the transitions. In the swinging regime, the region of the high principal tensions periodically oscillates, whereas that of the high isotropic tensions is almost unchanged. Due to the strain-hardening property of the membrane, the deformation is limited but the membrane tension increases monotonically with the capillary number. We have quantitatively compared our numerical results with former experimental results. It indicates that a membrane isotropic tension O(10{-6} N/m) is high enough for molecular release from RBCs and that the typical maximum membrane principal tension for haemolysis would be O(10{-4} N/m). These findings are useful to clarify not only the membrane rupture but also the mechanotransduction of RBCs.
Takuji Ishikawa - One of the best experts on this subject based on the ideXlab platform.
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rheology of a dense suspension of spherical capsules under Simple Shear Flow
Journal of Fluid Mechanics, 2016Co-Authors: Daiki Matsunaga, Takami Yamaguchi, Yohsuke Imai, Takuji IshikawaAbstract:We present a numerical analysis of the rheology of a dense suspension of spherical capsules in Simple Shear Flow in the Stokes Flow regime. The behaviour of neo-Hookean capsules is simulated for a volume fraction up to ${\it\phi}=0.4$ by graphics processing unit computing based on the boundary element method with a multipole expansion. To describe the specific viscosity using a polynomial equation of the volume fraction, the coefficients of the equation are calculated by least-squares fitting. The results suggest that the effect of higher-order terms is much smaller for capsule suspensions than rigid sphere suspensions; for example, $O({\it\phi}^{3})$ terms account for only 8 % of the specific viscosity even at ${\it\phi}=0.4$ for capillary numbers $Ca\geqslant 0.1$ . We also investigate the relationship between the deformation and orientation of the capsules and the suspension rheology. When the volume fraction increases, the deformation of the capsules increases while the orientation angle of the capsules with respect to the Flow direction decreases. Therefore, both the specific viscosity and the normal stress difference increase with volume fraction due to the increased deformation, whereas the decreased orientation angle suppresses the specific viscosity, but amplifies the normal stress difference.
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membrane tension of red blood cells pairwisely interacting in Simple Shear Flow
Journal of Biomechanics, 2013Co-Authors: Toshihiro Omori, Takuji Ishikawa, Yohsuke Imai, Takami YamaguchiAbstract:Flow-induced membrane tension contributes to the release of molecules by red blood cells (RBCs), and extremely high tension may cause haemolysis. Here, we investigated the membrane tension of RBCs during pairwise interactions in Simple Shear Flow, given that pairwise interactions form the basis of many-body interactions. RBCs were modelled as capsules with a two-dimensional hyperelastic membrane, and large deformations were solved by the finite element method. Due to the small size of the RBCs, surrounding fluid motion was estimated as a Stokes Flow and solved by the boundary element method. The results showed that the maximum isotropic tension appeared around the dimple of the biconcave surface and not around the rim. A comparison of the results with solitary cases indicated that the maximum principal tension and isotropic tension were significantly increased by cell–cell interaction effects. As the volume fraction of RBCs is large under physiological conditions, as well as in blood Flow in vitro, cell–cell interactions must be analysed carefully when considering mechanotransduction and haemolysis in blood Flow.
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tension of red blood cell membrane in Simple Shear Flow
Physical Review E, 2012Co-Authors: Toshihiro Omori, Dominique Barthesbiesel, Takuji Ishikawa, Yohsuke Imai, Annevirginie Salsac, Takami YamaguchiAbstract:When a red blood cell (RBC) is subjected to an external Flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a Simple Shear Flow and the resulting elastic tensions on the membrane. The large deformation of the red blood cell is modelled by coupling a finite element method to solve the membrane mechanics and a boundary element method to solve the Flows of the internal and external liquids. Depending on the capillary number Ca, ratio of the viscous to elastic forces, we observe three kinds of RBC motion: tumbling at low Ca, swinging at larger Ca, and breathing at the transitions. In the swinging regime, the region of the high principal tensions periodically oscillates, whereas that of the high isotropic tensions is almost unchanged. Due to the strain-hardening property of the membrane, the deformation is limited but the membrane tension increases monotonically with the capillary number. We have quantitatively compared our numerical results with former experimental results. It indicates that a membrane isotropic tension O(10{-6} N/m) is high enough for molecular release from RBCs and that the typical maximum membrane principal tension for haemolysis would be O(10{-4} N/m). These findings are useful to clarify not only the membrane rupture but also the mechanotransduction of RBCs.
Yohsuke Imai - One of the best experts on this subject based on the ideXlab platform.
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rheology of a dense suspension of spherical capsules under Simple Shear Flow
Journal of Fluid Mechanics, 2016Co-Authors: Daiki Matsunaga, Takami Yamaguchi, Yohsuke Imai, Takuji IshikawaAbstract:We present a numerical analysis of the rheology of a dense suspension of spherical capsules in Simple Shear Flow in the Stokes Flow regime. The behaviour of neo-Hookean capsules is simulated for a volume fraction up to ${\it\phi}=0.4$ by graphics processing unit computing based on the boundary element method with a multipole expansion. To describe the specific viscosity using a polynomial equation of the volume fraction, the coefficients of the equation are calculated by least-squares fitting. The results suggest that the effect of higher-order terms is much smaller for capsule suspensions than rigid sphere suspensions; for example, $O({\it\phi}^{3})$ terms account for only 8 % of the specific viscosity even at ${\it\phi}=0.4$ for capillary numbers $Ca\geqslant 0.1$ . We also investigate the relationship between the deformation and orientation of the capsules and the suspension rheology. When the volume fraction increases, the deformation of the capsules increases while the orientation angle of the capsules with respect to the Flow direction decreases. Therefore, both the specific viscosity and the normal stress difference increase with volume fraction due to the increased deformation, whereas the decreased orientation angle suppresses the specific viscosity, but amplifies the normal stress difference.
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membrane tension of red blood cells pairwisely interacting in Simple Shear Flow
Journal of Biomechanics, 2013Co-Authors: Toshihiro Omori, Takuji Ishikawa, Yohsuke Imai, Takami YamaguchiAbstract:Flow-induced membrane tension contributes to the release of molecules by red blood cells (RBCs), and extremely high tension may cause haemolysis. Here, we investigated the membrane tension of RBCs during pairwise interactions in Simple Shear Flow, given that pairwise interactions form the basis of many-body interactions. RBCs were modelled as capsules with a two-dimensional hyperelastic membrane, and large deformations were solved by the finite element method. Due to the small size of the RBCs, surrounding fluid motion was estimated as a Stokes Flow and solved by the boundary element method. The results showed that the maximum isotropic tension appeared around the dimple of the biconcave surface and not around the rim. A comparison of the results with solitary cases indicated that the maximum principal tension and isotropic tension were significantly increased by cell–cell interaction effects. As the volume fraction of RBCs is large under physiological conditions, as well as in blood Flow in vitro, cell–cell interactions must be analysed carefully when considering mechanotransduction and haemolysis in blood Flow.
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tension of red blood cell membrane in Simple Shear Flow
Physical Review E, 2012Co-Authors: Toshihiro Omori, Dominique Barthesbiesel, Takuji Ishikawa, Yohsuke Imai, Annevirginie Salsac, Takami YamaguchiAbstract:When a red blood cell (RBC) is subjected to an external Flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a Simple Shear Flow and the resulting elastic tensions on the membrane. The large deformation of the red blood cell is modelled by coupling a finite element method to solve the membrane mechanics and a boundary element method to solve the Flows of the internal and external liquids. Depending on the capillary number Ca, ratio of the viscous to elastic forces, we observe three kinds of RBC motion: tumbling at low Ca, swinging at larger Ca, and breathing at the transitions. In the swinging regime, the region of the high principal tensions periodically oscillates, whereas that of the high isotropic tensions is almost unchanged. Due to the strain-hardening property of the membrane, the deformation is limited but the membrane tension increases monotonically with the capillary number. We have quantitatively compared our numerical results with former experimental results. It indicates that a membrane isotropic tension O(10{-6} N/m) is high enough for molecular release from RBCs and that the typical maximum membrane principal tension for haemolysis would be O(10{-4} N/m). These findings are useful to clarify not only the membrane rupture but also the mechanotransduction of RBCs.
Michael D. Graham - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of a single red blood cell in Simple Shear Flow
Physical Review E, 2015Co-Authors: Kushal Sinha, Michael D. GrahamAbstract:This work describes simulations of a red blood cell (RBC) in Simple Shear Flow, focusing on the dependence of the cell dynamics on the spontaneous curvature of the membrane. The results show that an oblate spheroidal spontaneous curvature maintains the dimple of the RBC during tank-treading dynamics as well as exhibits off-Shear-plane tumbling consistent with the experimental observations of Dupire et al. [J. Dupire,M. Socol, and A.Viallat, Proc. Natl. Acad. Sci.USA109, 20808 (2012)] and their hypothesis of an inhomogeneous spontaneous shape. As the Flow strength (capillary number Ca) is increased at a particular viscosity ratio between inner and outer fluid, the dynamics undergo transitions in the following sequence: tumbling, kayaking or rolling, tilted tank-treading, oscillating-swinging, swinging, and tank-treading. The tilted tank-treading (or spinning frisbee) regime has been previously observed in experiments but not in simulations. Two distinct classes of regime are identified: a membrane reorientation regime, where the part of membrane that is at the dimple at restmoves to the rim and vice versa, is observed in motions at high Ca such as tilted tank-treading, oscillating-swinging, swinging, and tank-treading, and a nonreorientation regime, where the part of themembrane starting from the dimple stays at the dimple, is observed in motions at low Ca such as rolling, tumbling, kayaking, and flip-flopping.
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Shear-induced diffusion in dilute curved fiber suspensions in Simple Shear Flow
Physics of Fluids, 2014Co-Authors: Jianghui Wang, Michael D. Graham, Daniel J. KlingenbergAbstract:Shear-induced self-diffusion of fibers suspended in an incompressible Newtonian fluid in Simple Shear Flow at low Reynolds number is studied by simulation. Two models are employed: a linked rigid rod model and a bead chain model. Hydrodynamic interactions are neglected in both models. The Shear-induced diffusivity of suspensions of fibers increases with increasing concentration and increasing static friction between contacts. The diffusivities in both the gradient and vorticity directions are larger for suspensions of curved fibers than for suspensions of straight fibers. For suspensions of curved fibers, significant enhancements in the diffusivity in the gradient direction are observed. The enhanced diffusivities are attributed to fiber drift observed in prior work for isolated curved fibers [J. Wang, E. J. Tozzi, M. D. Graham, and D. J. Klingenberg, “Flipping, scooping, and spinning: Drift of rigid curved nonchiral fibers in Simple Shear Flow,” Phys. Fluids 24, 123304 (2012)]. Here, for some initial ori...
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Flipping, scooping, and spinning: Drift of rigid curved nonchiral fibers in Simple Shear Flow
Physics of Fluids, 2012Co-Authors: Jianghui Wang, Michael D. Graham, Emilio J. Tozzi, Daniel J. KlingenbergAbstract:The motion of isolated, rigid, neutrally-buoyant, non-Brownian, curved, nonchiral fibers in Simple Shear Flow of an incompressible Newtonian fluid at low Reynolds number is studied by computer simulation. For some initial orientations, fibers with small curvature drift steadily in the gradient direction without external forces or torques. The average drift velocity and direction depend on the fiber aspect ratio, curvature, and initial orientation. The drift results from the coupling of rotational and translational dynamics, and the combined effects of flipping, scooping, and spinning motions of the fiber.
Toshihiro Omori - One of the best experts on this subject based on the ideXlab platform.
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membrane tension of red blood cells pairwisely interacting in Simple Shear Flow
Journal of Biomechanics, 2013Co-Authors: Toshihiro Omori, Takuji Ishikawa, Yohsuke Imai, Takami YamaguchiAbstract:Flow-induced membrane tension contributes to the release of molecules by red blood cells (RBCs), and extremely high tension may cause haemolysis. Here, we investigated the membrane tension of RBCs during pairwise interactions in Simple Shear Flow, given that pairwise interactions form the basis of many-body interactions. RBCs were modelled as capsules with a two-dimensional hyperelastic membrane, and large deformations were solved by the finite element method. Due to the small size of the RBCs, surrounding fluid motion was estimated as a Stokes Flow and solved by the boundary element method. The results showed that the maximum isotropic tension appeared around the dimple of the biconcave surface and not around the rim. A comparison of the results with solitary cases indicated that the maximum principal tension and isotropic tension were significantly increased by cell–cell interaction effects. As the volume fraction of RBCs is large under physiological conditions, as well as in blood Flow in vitro, cell–cell interactions must be analysed carefully when considering mechanotransduction and haemolysis in blood Flow.
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tension of red blood cell membrane in Simple Shear Flow
Physical Review E, 2012Co-Authors: Toshihiro Omori, Dominique Barthesbiesel, Takuji Ishikawa, Yohsuke Imai, Annevirginie Salsac, Takami YamaguchiAbstract:When a red blood cell (RBC) is subjected to an external Flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a Simple Shear Flow and the resulting elastic tensions on the membrane. The large deformation of the red blood cell is modelled by coupling a finite element method to solve the membrane mechanics and a boundary element method to solve the Flows of the internal and external liquids. Depending on the capillary number Ca, ratio of the viscous to elastic forces, we observe three kinds of RBC motion: tumbling at low Ca, swinging at larger Ca, and breathing at the transitions. In the swinging regime, the region of the high principal tensions periodically oscillates, whereas that of the high isotropic tensions is almost unchanged. Due to the strain-hardening property of the membrane, the deformation is limited but the membrane tension increases monotonically with the capillary number. We have quantitatively compared our numerical results with former experimental results. It indicates that a membrane isotropic tension O(10{-6} N/m) is high enough for molecular release from RBCs and that the typical maximum membrane principal tension for haemolysis would be O(10{-4} N/m). These findings are useful to clarify not only the membrane rupture but also the mechanotransduction of RBCs.
