Enucleated incompressible red blood cells in shear flow: Theoretical analysis of shape instabilities
Abstract
Red blood cells (RBCs) are essential for oxygen transport, and their remarkable ability to undergo significant deformations during flow is a crucial feature for their physiological function. At intermediate shear rates typical of the microcirculation, RBCs can adopt complex, multi-lobed shapes, signifying a dynamic instability. Here we adopt a perturbative theoretical framework of a quasispherical RBC under external shear flow to study such shape instabilities. To better capture RBC maturation and enucleation, we first extend the framework to explicitly account for different excess areas between the stress-free and current membrane shapes. We revisit the reduced equations of motion obtained for an ellipsoidally-shaped RBC, and demonstrate the effect of different excess areas and initial orientation on the dynamical trajectories. Then, we introduce additional spatial modes and show that an emerging instability critically depends on the RBC's shear and bending moduli, the internal to external viscosity ratio, and the excess area, mainly through the RBC's membrane tension. We also study the instability-induced saturation of the membrane tension, and the resulting excess area redistribution at long times. The theoretical framework and the emerging picture of the different instabilities provide insights into the emergence of stomatocyte and trilobe shapes exhibited by RBCs under external flow.
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BibTeX
@article{moriel2026enucleated,
title = {{Enucleated incompressible red blood cells in shear flow: Theoretical analysis of shape instabilities}},
author = {Avraham Moriel and Howard Stone and Simon Mendez},
journal = {Physical Review Fluids},
year = {2026},
month = oct,
doi = {10.1103/nw8l-tsps},
eprint = {2606.19072},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05798471v1},
note = {CC BY-ND 4.0},
}
RIS
TY - JOUR
TI - Enucleated incompressible red blood cells in shear flow: Theoretical analysis of shape instabilities
AU - Avraham Moriel
AU - Howard Stone
AU - Simon Mendez
PY - 2026
DA - 2026/10/13
JO - Physical Review Fluids
DO - 10.1103/nw8l-tsps
UR - https://hal.science/hal-05798471v1
AB - Red blood cells (RBCs) are essential for oxygen transport, and their remarkable ability to undergo significant deformations during flow is a crucial feature for their physiological function. At intermediate shear rates typical of the microcirculation, RBCs can adopt complex, multi-lobed shapes, signifying a dynamic instability. Here we adopt a perturbative theoretical framework of a quasispherical RBC under external shear flow to study such shape instabilities. To better capture RBC maturation and enucleation, we first extend the framework to explicitly account for different excess areas between the stress-free and current membrane shapes. We revisit the reduced equations of motion obtained for an ellipsoidally-shaped RBC, and demonstrate the effect of different excess areas and initial orientation on the dynamical trajectories. Then, we introduce additional spatial modes and show that an emerging instability critically depends on the RBC's shear and bending moduli, the internal to external viscosity ratio, and the excess area, mainly through the RBC's membrane tension. We also study the instability-induced saturation of the membrane tension, and the resulting excess area redistribution at long times. The theoretical framework and the emerging picture of the different instabilities provide insights into the emergence of stomatocyte and trilobe shapes exhibited by RBCs under external flow.
SN - 2469-990X
ER -