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Blood in flow. Basic concepts
Published in Annie Viallat, Manouk Abkarian, Dynamics of Blood Cell Suspensions in Microflows, 2019
Etienne Loiseau, Annie Viallat, Manouk Abkarian
In fact, as it is described in several chapters of this book, at low shear rates, RBCs aggregate and stack into three-dimensional structures called rouleaux, which are piles of RBCs analogous to piles of coins. Fibrinogen and globulin proteins present in the plasma promote this aggregation as will be discussed in Chapter 6. At a higher shear rate, for example for physiological shear rates (typically ≫100s−1), rouleaux fragment and cells circulate individually. This leads to a decrease in blood viscosity. At high shear, the RBCs elongate and align in the direction of flow, facilitating their movement relative to each other and further reducing blood viscosity (the process will be challenged in Chapter 5).
Biocompatibility and Biomaterials
Published in Sirshendu De, Anirban Roy, Hemodialysis Membranes, 2017
Erythrocytes or red blood cells can aggregate under abnormal conditions, where the individual cells “stick” together and give the impression of a viscous fluid behaving like glue. The aggregation forms in a special way, forming a rouleaux.13 Rouleaux are stacks of erythrocytes, and stacks can form due to the unique discoid shape of the cells. It occurs in normal blood under low-flow conditions or at stasis. The underlining mechanism for rouleaux formation is depletion of high-molecular-weight proteins, like fibrinogen, also known as chemiosmotic hypothesis for aggregation. Aggregation can occur under various conditions such as infection, inflammatory and connective tissue disorders, and cancers.
Nonsimilar numerical analysis for the mixed convective flow of Casson fluid with thermal radiations and chemical reactions
Published in Waves in Random and Complex Media, 2022
Muavia Mansoor, Yasir Nawaz, Qazi Mahmood Ul-Hassan
Casson fluid is one type of non-Newtonian fluid (NNF) that belong to shear-thinning liquids and cause yield stress. It has an infinite viscosity at zero shear rate, and at a constant shear rate, it has zero viscosity, i.e. it performs like a solid if the yield stress is larger than the shear stress on the fluid. In contrast, it starts to move if the shear stress is more important than the yield stress. Due to some elements such as fibrinogen, protein, human red blood cells, and globulin in aqueous base plasma, it can produce a chainlike structure, which is known as rouleaux. Numerous studies have been performed to discover the Casson fluid over flat/cylindrical stretched sheets under different physical situations. The Casson fluid model explains the blood flow which is highly helpful in modeling blood hemodialysis and oxygenators. An analysis of Casson rheological fluid with gold nanoparticles under the influence of gravitational and magnetic forces was given by Hussain et al. [1]. A theoretical framework for the mathematical modeling of the Casson rheological fluid was developed by Nazir et al. [2]. Shaw et al. [3] examined nonlinear thermal effects on Casson fluid over the flat horizontal plate with a convective boundary. Ramesh and Devakar [4] considered slip boundary conditions. The current useful efforts upon Casson fluid flow with the help of various physical impacts are discovered in Refs. [5–8]. The influence of heat and mass transfer in Casson fluid flow on the porous stretching surface was given by Raju et al. [9]. Maity et al. [10] examined the magnetohydrodynamic Casson fluid with suction/injection effects through the surface. On thermally corrugated porous enclosure equipped with Casson liquid suspension: Finite element thermal analysis was examined by Rehman et al. [11].