Dynamic characteristics of a deformable capsule in a simple shear flow

Abstract

The dynamic characteristics of a two-dimensional deformable capsule in a simple shear flow are studied with an immersed boundary-lattice Boltzmann method. Simulations are conducted by varying the Reynolds number (Re) from 0.0125 to 2000 and the dimensionless shear rate (G) from 0.001 to 0.5. The G-Re plane can be divided into four regions according to the deformation dependence on the parameters considered: viscous dominant, inertia dominant, transitional and anomalous regions. There are four typical dynamic behaviours over the G-Re plane: steady deformation, pre-rupture state, quasi-steady deformation and continuous elongation. Analysis indicates that the pressure distribution and its variations due to the interplay of the fluid inertia force, the viscous shear stress and the membrane elastic force determines the complex behaviours of the capsule. The effects of the bending rigidity and the internal-to-external viscosity ratio on the dynamics of the capsule are further studied. It is found that the capsule experiences smaller deformation when the higher bending rigidity is included, and the low bending rigidity does not have a remarkable influence on the capsule deformation. The capsule normally experiences smaller deformation due to the increase of the internal-to-external viscosity ratio.

An IB-LBM for FSI Problems Involving Viscoelastic Fluids and Complex Geometries

“…The interaction between the fluid and the solid structure is achieved by using the immersed boundary method [16,11,24]. The immersed boundary-lattice Boltzmann method used here has been extensively validated in different flows in our previous work [16], and details of this method and validation cases as well as its applications can be found in our previous studies [16,11,25,26,27,28]. Here, this method is further validated by several cases: 2D Oldroyd-B channel flow, 2D lid-driven Oldroyd-B cavity flow, 2D Oldroyd-B flow over a confined cylinder, a 2D neutrally buoyant particle migration in an Oldroyd-B Couette flow, a 3D neutrally buoyant spherical particle rotation in an Oldroyd-B shear flow, a spherical particle settling under gravity in a Newtonian fluid, and a 3D spherical capsule deformation in a channel with a the square cross-section.…”

IB-LBM study of non-Newtonian flexible capsule flows in contraction-expansion microchannels

“…The fluid-structure system is solved by the IB-LBM [13,8,7]. This method employs the lattice Boltzmann method to solve both the fluid dynamics and the constitutive equations of viscoelastic fluids.…”

Recent trends and progress in the immersed boundary method

“…1,60 Afterwards, the original IBM and its developed versions have been extensively used in heart and blood flows. 61–68 At Stokes and low Reynolds number regimes, the IBM has been extensively used to cell/particulate flows, 13,17,46,69–84 cilia 85–87 and microswimmers. 88–94 For moderate Reynolds number flows, the IBM has been applied to study filament/flag flapping, 9,11,24,27,37,95–108 insect flying and fish swimming, 11,15,24,25,44,109…”

“…1,60 Afterwards, the original IBM and its developed versions have been extensively used in heart and blood flows. [61][62][63][64][65][66][67][68] At Stokes and low Reynolds number regimes, the IBM has been extensively used to cell/particulate flows, 13,17,46,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] cilia [85][86][87] and microswimmers. [88][89][90][91][92][93][94] For moderate Reynolds number flows, the IBM has been applied to study filament/flag flapping, 9,11,24,27,37,[95][96][97][98][99]…”