Shape oscillations of elastic particles in shear flow.
Particle suspensions are common to biological fluid flows; for example, flow of red- and white-blood cells, and platelets. In medical technology, current and proposed methods for drug delivery use membrane-bounded liquid capsules for transport via the microcirculation. In this paper, we consider a 3D linear elastic particle inserted into a Newtonian fluid and investigate the time-dependent deformation using a numerical simulation. Specifically, a boundary element technique is used to investigate the motion and deformation of initially spherical or spheroidal particles in bounded linear shear flow. The resulting deformed shapes reveal a steady-state profile that exhibits a 'tank-treading' motion for initially spherical particles. Wall effects on particle trajectory are seen to include a modified Jeffrey׳s orbit for spheroidal inclusions with a period that varies inversely with the strength of the shear flow. Alternately, spheroidal inclusions may exhibit either a 'tumbling' or 'trembling' motion depending on the initial particle aspect ratio and the capillary number (i.e., ratio of fluid shear to elastic restoring force). We find for a capillary number of 0.1, a tumbling mode transitions to a trembling mode at an aspect ratio of 0.87 (approx.), while for a capillary number of 0.2, this transition takes place at a lower aspect ratio. These oscillatory modes are consistent with experimental observations involving similarly shaped vesicles and thus serves to validate the use of a simple elastic constitutive model to perform relevant physiological flow calculations.
Dept. of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, USA.
Dhananjay Radhakrishnan
DR
Subramaniam
Dept. of Mechanical Engineering, Gannon University, Erie, PA, USA. Electronic address: gee004@Gannon.edu.
David J
DJ
Gee
D004548:Elasticity; D004912:Erythrocytes / Q000502:physiology*; D007962:Leukocytes / Q000502:physiology*; D009038:Motion; D033081:Shear Strength; D013535:Suspensions; D014783:Viscosity
D013535:Suspensions
Boundary element method; Shape dynamics; Viscous flow; Wall-effects; linear elasticity