Swirling of vesicles: Shapes and dynamics in Poiseuille flow as a model of RBC microcirculation
We report on a systematic numerical exploration of the vesicle dynamics in a channel, which is a model of red blood cells in microcirculation. We find a spontaneous transition, called swirling, from straight motion with axisymmetric shape to a motion along a helix with a stationary deformed shape that rolls on itself and spins around the flow direction. We also report on a planar oscillatory motion of the mass center, called three-dimensional snaking for which the shape deforms periodically. Both emerge from supercritical pitchfork bifurcation with the same threshold. The universality of these oscillatory dynamics emerges from Hopf bifurcations with two order parameters. These two oscillatory dynamics are put in the context of vesicle shape and dynamics in the parameter space of reduced volume v, capillary number, and confinement. Phase diagrams are established for v = 0.95, v = 0.9, and v = 0.85 showing that oscillatory dynamics appears if the vesicle is sufficiently deflated. Stationary shapes (parachute/bullet/peanut, croissant, and slipper) are fixed points, while swirling and snaking are characterized by two limit cycles.
Jinming Lyu, Paul G. Chen, Alexander Farutin, Marc Jaeger, Chaouqi Misbah, et al.. Swirling of vesicles: Shapes and dynamics in Poiseuille flow as a model of RBC microcirculation. Physical Review Fluids, 2023, 8 (2), pp.L021602. ⟨10.1103/PhysRevFluids.8.L021602⟩. ⟨hal-03979358v2⟩
Journal: Physical Review Fluids
Date de publication: 01-01-2023