The effect of parallel combined steady and oscillatory shear flows on blood and polymer solutions

Vaz

Cerejo

et al. 2018

Journal of Rheology

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

Section: Introductionmentioning

confidence: 99%

Rheological behavior of human blood in uniaxial extensional flow

Vaz

Cerejo

et al. 2018

Journal of Rheology

“…Although accompanied by the disruption of the aggregates of RBC at high shear rates, it is the deformability of RBC that becomes the main cause of the viscoelastic properties of blood. Vlastos et al (1997) investigated the blood response in steady and in SAOS using a strain amplitude sweep at a constant frequency of 0.5 Hz, as well as under a frequency sweep at constant strain amplitude. Constant steady shear rates were superimposed during oscillatory shear measurements in order to analyze their combined effect on the viscoelastic characteristics.…”

Section: Referencementioning

confidence: 99%

“…Other investigations have focused on transient and oscillatory flows, usually conducted under small amplitude deformation conditions (Vlastos et al, 1997;Picart et al, 1998;Yilmaz and Gundogdu, 2008). The flow of blood in physiological conditions typically involves large deformations, large deformation rates and periodic forcing with large amplitude (Caro et al, 1974) and consequently valuable information can be obtained from the characterization of blood under more extreme conditions, such as in large amplitude oscillatory shear flow (LAOS) (Sousa et al, 2013) or under conditions of extensional flow (Sousa et al, 2011) since these can be observed in diseased vessels (e.g.…”

Section: Introductionmentioning

confidence: 99%

A review of hemorheology: Measuring techniques and recent advances

Pinho

Alves

et al. 2016

Korea-Aust. Rheol. J.

Significant progress has been made over the years on the topic of hemorheology, not only in terms of the development of more accurate and sophisticated techniques, but also in terms of understanding the phenomena associated with blood components, their interactions and impact upon blood properties. The rheological properties of blood are strongly dependent on the interactions and mechanical properties of red blood cells, and a variation of these properties can bring further insight into the human health state and can be an important parameter in clinical diagnosis. In this article, we provide both a reference for hemorheological research and a resource regarding the fundamental concepts in hemorheology. This review is aimed at those starting in the field of hemodynamics, where blood rheology plays a significant role, but also at those in search of the most up-to-date findings (both qualitative and quantitative) in hemorheological measurements and novel techniques used in this context, including technical advances under more extreme conditions such as in large amplitude oscillatory shear flow or under extensional flow, which impose large deformations comparable to those found in the microcirculatory system and in diseased vessels. Given the impressive rate of increase in the available knowledge on blood flow, this review is also intended to identify areas where current knowledge is still incomplete, and which have the potential for new, exciting and useful research. We also discuss the most important parameters that can lead to an alteration of blood rheology, and which as a consequence can have a significant impact on the normal physiological behavior of blood.

“…In effect, at low shear rates RBCs may form aggregated structures, named rouleaux, the dynamics of which impact severely on blood rheology [19]. The aggregation of blood cells depends on the protein concentration in plasma (a good example that minor amounts of an additive can have a large impact in fluid structure and rheology) and on the shear rate and is a reversible process that leads to a viscoelastic, shear-thinning and thixotropic behavior of blood [16,17]. As such, blood shear viscosity depends on a number of variables, namely, hematocrit, the shear rate and even the vessel diameter, the latter known as the Fåhraeus-Lindqvist effect [10].…”

Section: Introductionmentioning

confidence: 99%

“…Vlastos et al [16] studied the combination of steady and oscillatory shear on the human blood flow behavior. For this purpose, they also used blood analogue solutions made from high molecular weight polymers dissolved in water, namely aqueous solutions of polyacrylamide and xanthan gum at different concentrations.…”

Section: Introductionmentioning

confidence: 99%

Flow of a Blood Analogue Solution Through Microfabricated Hyperbolic Contractions

Computational Methods in Applied Sciences

Pinho

et al. 2010

This version is available at https://strathprints.strath.ac.uk/41317/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Abstract The flow of a blood analogue solution past a microfabricated hyperbolic contraction followed by an abrupt expansion was investigated experimentally. The shape of the contraction was designed in order to impose a nearly constant strain rate to the fluid along the centerline of the microgeometry. The flow patterns of the blood analogue solution and of a Newtonian reference fluid (deionized water), captured using streak line imaging, are quite distinct and illustrate the complex behavior of the blood analogue solution flowing through the microgeometry. The flow of the blood analogue solution shows elastic-driven effects with vortical structures emerging upstream of the contraction, which are absent in Newtonian fluid flow. In both cases the flow also develops instabilities downstream of the expansion but these are inertia driven. Therefore, for the blood analogue solution at high flow rates the competing effects of inertia and elasticity lead to complex flow patterns and unstable flow develops. Flow of a Blood Analogue Solution Through