Paper Number
BA14
Session
Biological and Active Matters
Title
Transient modeling of viscoelasticity, thixotropy, and flow inhomogeneities (syneresis) in human blood rheology
Presentation Date and Time
October 16, 2018 (Tuesday) 9:50
Track / Room
Track 6 / Tanglewood
Authors
- Horner, Jeffrey S. (University of Delaware, Chemical and Biomolecular Engineering)
- Beris, Antony N. (University of Delaware, Chemical and Biomolecular Engineering)
- Wagner, Norman J. (University of Delaware)
Author and Affiliation Lines
Jeffrey S. Horner, Antony N. Beris, and Norman J. Wagner
Chemical and Biomolecular Engineering, University of Delaware, Newark, DE
Speaker / Presenter
Horner, Jeffrey S.
Text of Abstract
Blood is a complex fluid primarily composed of deformable red blood cells (RBCs) suspended in an aqueous plasma. As a result of aggregates of RBCs, termed rouleaux, that form at rest and under low shear, blood exhibits interesting rheological signatures including a shear thinning behavior, viscoelasticity, and thixotropy. At low shear conditions, a phenomenon known as syneresis can also occur, in which a RBC depletion layer forms near the walls of the measurement device due, in part, to the relatively large aggregate size and the significant difference between the plasma and bulk viscosities. Understanding the complex rheology of blood is critical both for developing blood flow simulations throughout the circulatory system and for engineering rheological diagnostics tools for diseases that have been shown to affect the rheology of blood. In this work, we present new data on step shear change and cessation measurements for healthy human blood using an improved measurement protocol developed in our laboratory [1]. Using these data, we propose a two fluid model, which is incorporated into a previously developed model for transient blood rheology [2], to capture the effects of syneresis. This analysis helped to better identify the complex viscoelastic behavior associated with rouleaux. The structure-dependent viscoelasticity is characterized through a viscoelastic network approach. The new model is compared to the new measurements and demonstrates a good fit to the experimental data. Additionally, the new model improves upon the previous model predictions for unidirectional large amplitude oscillatory shear, demonstrating the full capability of the new model. This work helps to elucidate the connection between the bulk flow properties of blood and the underlying microstructure, and further, introduces transient modeling concepts that can be applied to a broader range of viscoelastic and thixotropic fluids. [1] Horner et al., Clin. Hemorheol. Microcirc., Preprint, (2018). [2] Horner et al., J. Rheol., 62(2), (2018).