Deformation of a biconcave-discoid capsule in extensional flow and electric field

TL;DR

This study investigates how uniaxial extensional flow and electric fields deform biconcave-discoid capsules, modeling red blood cells, revealing shape transitions and membrane stress behaviors relevant for bioengineering applications.

Contribution

It provides a detailed numerical analysis of RBC-like capsule deformation under flow and electric fields using boundary integral methods and Skalak membrane law, highlighting shape transitions.

Findings

Biconcave to prolate spheroid transition observed.

Membrane stresses are significant during deformation.

Electric stresses influence capsule shape and stability.

Abstract

Biconcave-discoid (empirical shape of a red blood cell) capsule finds numerous applications in the field of bio-fluid dynamics and rheology, apart from understanding the behavior of red blood cells (RBC) in blood flow. A detailed analysis is, therefore, carried out to understand the effects of the uniaxial extensional flow and electric field on the deformation of a RBC and biconcave-discoid polymeric capsule in the axisymmetric regime. The transient deformation is computed numerically using axisymmetric boundary integral method for Stokes flow considering the Skalak membrane constitutive law as the model for the area incompressible RBC/biconcave-discoid capsule membrane. A remarkable biconcave-discoid to prolate spheroid transition is observed when the elastic energy is overcome by the viscous or Maxwell electric stresses. Moreover, the significance of membrane stresses developed during the deformation and at steady state and different modes of deformation are presented. This study should be useful in designing an artificial system involving biological cells under an electric field.