Abstract
Numerical simulations supported by previously published experimental data are used to compare the impact of the internal fluid viscosity and the membrane viscosity on a tank-treading red blood cell. The method used is based on a continuum framework both for the fluid and the membrane, their interaction being ensured thanks to the immersed boundary method. The finite-strain model implemented to account for membrane viscosity assumes a free energy form that leads to an additive decomposition of the equilibrium and nonequilibrium stresses. It also assumes that the stress tensor can be separated into a deviatoric part and a hydrostatic part, which are independent. Only the deviatoric part is accounted for in this study. Both the viscosities of the cytoplasm and of the membrane yield a decrease of the tank-treading frequency, with only moderate changes in the deformation of the red blood cell. However, it is shown that the values of tank-treading frequency from the literature cannot be explained by the internal fluid viscosity only. On the contrary, adding the membrane dissipation produces a good agreement with experimental results when using acceptable values of the internal fluid and membrane viscosities. In addition, this study proposes a direct inference of the value of the membrane viscosity as a function of the shear rate from the comparison between simulations and experiments and confirms experimental results that highlighted the shear-thinning behavior of the red blood cell membrane.
1 More- Received 27 November 2020
- Accepted 29 March 2021
DOI:https://doi.org/10.1103/PhysRevFluids.6.043602
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