Rheological behavior of human blood in uniaxial extensional flow

Abstract

We present an investigation of the rheological behavior of whole human blood under uniaxial extensional flow. For that purpose, capillary breakup experiments were carried out by combining the slow retraction method, high-speed imaging techniques and an immiscible oil bath. The use of the oil bath was aimed at reducing liquid loss by evaporation and to reduce light refraction effects, thus allowing the visualization of the blood cells during the filament thinning. Extensional relaxation times were measured for whole blood samples collected from a total of thirteen healthy adult volunteers from both genders, with hematocrit levels between 38.7% and 46.3%. For this range of red blood cell concentrations, the variation of the extensional relaxation time is small, with the average extensional relaxation times measured in air and in oil being 11430 s and 25947 s, respectively. An increase of the red blood cells concentration leads to an increase of the bulk viscosity of the sample, which delays the thinning of the filament and consequently the time to breakup. In addition, blood aging was found to reduce the relaxation time while the absence of anticoagulant increases it significantly.2

Blood Viscoelasticity Measurement Using Interface Variations in Coflowing Streams under Pulsatile Blood Flows

“…The viscometer had operated at a wider range of frequency from ω = 0.3 rad/s to ω = 700 rad/s [29]. The previous study indicated that the time constant of whole blood was obtained as λcv = 1.5-13.4 ms for shear flow [29], and λcv = 114-259 ms for extensional flow [30]. On the other hand, under periodic blood flow in the microfluidic system, Figure 6A-b showed the simple fluidic circuit model of the microfluidic system.…”

A parametric investigation of blood flow in a wedge with non‐uniform viscosity and wall friction

“…The idea of using viscosity distribution function as appears in (25) is due to the theoretical and experimental results of blood viscosity behavior that obtained by Cerny and Walawender [4] and Pontrelli [44] and many others [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] as appear in…”

“…The idea to use the non-Newtonian fluid was due to the fact that the Newtonian model does not give an appropriate response to many discrepancies observed in experiments. [35][36][37][38][39][40][41][42][43] In this section a solution for the non-Newtonian case ( = 2) will be examined alongside edge conditions (30) and the normalized condition (20b). By substituting = 2 into Equations (9) and (15), we get:…”

“…Another evident to the rheological behavior of blood flow due to extensional stresses was found by Down et al [37] and Sousa et al, [38] while the latter has exhibited nonlinear viscoelastic behavior, such as the viscous component dominated over the elastic component. Some applications of blood rheological elastic part can be found in Campo-Deaño et al [39] Particularly, the tremendous effect of the nonlinear viscosity on the RBC non-Newtonian fluid behavior was demonstrated by Flormann et al [40] Advanced analytic and experimental models of blood and other rheological fluids have been proposed recently by [41][42][43]. However, those models are not fully completed and limited by geometry (flat plate [41] ) or being semi-empirical without a complete analytical model.…”

“…However, those models are not fully completed and limited by geometry (flat plate [41] ) or being semi-empirical without a complete analytical model. [41][42][43] Comparison will be performed here with the following studies. Beginning with the study of Pontrelli [44] that deals with the unsteady flow in a pipe based on Navier-Stokes (NS) equations including the non-linear viscosity.…”