Modeling Red Blood Cell Mechanics and Sub-Hemolytic Damage under Extreme Flow Conditions

Studying red blood cells (RBCs) under high-stress conditions is critical for understanding sub-hemolytic damage and the progression toward hemolysis caused by mechanical forces. Both shear and extensional stress contribute to membrane deformation and damage, though their mechanisms differ. In this work, we investigate RBC behavior under high shear and extensional flows using both one-component and two-component membrane models.

At higher stress levels, commonly used bending models based on Helfrich’s theory fail due to strain softening. To address this, we introduce a new bending model using a modified Taylor expansion that incorporates strain hardening. This new model demonstrates improved performance under extreme stress, validated against FEM results. Our RBC model's accuracy is further confirmed by good agreement of cell deformation index and final shape with experimental and numerical literature results across a wide range of stress levels. We also analyze the first principal strain field for localized membrane deformations and explore the impact of viscosity ratios on RBC dynamics at high stress.

Crucially, our model quantifies the dissociation between the cytoskeleton and lipid bilayer under both high shear and extensional stresses by quantifying the number of broken bonds, providing direct insight into sub-hemolytic damage. These advancements provide a comprehensive framework for studying RBC damage mechanisms relevant to physiological and biomedical flow environments.