non-Newtonian Blood Research Articles

CFD Analysis of Non-Newtonian Blood Flow through Human Carotid Artery Bifurcation: Carotid Sinus Susceptible to Atherosclerosis

CFD Analysis of Non-Newtonian Blood Flow through Human Carotid Artery Bifurcation: Carotid Sinus Susceptible to Atherosclerosis

The influence of non-Newtonian behaviors of blood on the hemodynamics past a bileaflet mechanical heart valve

This study employs extensive three-dimensional direct numerical simulations to investigate the hemodynamics around a bileaflet mechanical heart valve. In particular, this study focuses on assessing whether non-Newtonian rheological behaviors of blood, such as shear-thinning and yield stress behaviors, exert an influence on hemodynamics compared to the simplistic Newtonian behavior under both steady inflow and physiologically realistic pulsatile flow conditions. Under steady inflow conditions, the study reveals that blood rheology impacts velocity and pressure field variations, as well as the values of clinically important surface and time-averaged parameters like wall shear stress (WSS) and pressure recovery. Notably, this influence is most pronounced at low Reynolds numbers, gradually diminishing as the Reynolds number increases. For instance, surface-averaged WSS values obtained with the non-Newtonian shear-thinning power-law model exceed those obtained with the Newtonian model. At Re=750, this difference reaches around 67%, reducing to less than 1% at Re=5000. Correspondingly, pressure recovery downstream of the valve leaflets is lower for the shear-thinning blood than the constant viscosity one, with the difference decreasing as the Reynolds number increases. On the other hand, in pulsatile flow conditions, jets formed between the leaflets and the valve housing wall are shorter than steady inflow conditions. Additionally, surface-averaged wall shear stress and blood damage (BD) parameter values are higher (with differences more than 13% and 47%, respectively) during the peak stage of the cardiac cycle, especially for blood exhibiting non-Newtonian yield stress characteristics compared to the shear-thinning or constant viscosity characteristics. Therefore, blood non-Newtonian behaviors, including shear-thinning and yield stress behaviors, exert a considerable influence on the hemodynamics around a mechanical heart valve. All in all, the findings of this study demonstrate the importance of considering non-Newtonian blood behaviors when designing blood-contacting medical devices, such as mechanical heart valves, to enhance functionality and performance.

Peristaltic Flow of Jeffrey Fluid in an Inclined Porous Tube with Multi-Thrombosis

The fact that multiple thrombosis opposes blood flow and flow is rare in blood vessels is refined to a normal condition with catheter application. The inner surface of the circular blood arteries may not be smooth in the majority of diseased instances. Additionally, the small blood vessel peristalsis mechanism is formed. In this paper, we discuss a mathematical model for the flow of biological fluid (blood) in a circular tube with multi-thrombosis considered under peristaltic wave propagation. The blood flow in this tube is restricted due to the many thromboses present, and the flow is redesigned with the aid of a catheter. We model this non-Newtonian blood flow issue for Jeffrey fluid. In most pathological cases, the inner surface of the circular blood vessels may not be smooth. Further, the mechanism of the peristalsis is established for small blood vessels. Because of this biological phenomenon, the peristaltic movement of Jeffrey fluid in a porous annulus with slip is examined. Equations that govern energy and momentum are solved exactly, and graphical interpretation is made using mathematical software. Streamline graphs show the many thromboses that increase in height. The wall shear stress graphs show a sinusoidally advancing wave with peaks and dips of different amplitudes. This tube's unique crest and trough amplitude are caused by the presence of multiple thromboses. We obtained the impact of the pressure gradient on the permeability parameter (β). The pressure gradient falls as the permeability parameter rises.

Numerical-experimental estimation of the deformability of human red blood cells from rheometrical data

The deformability of human red blood cells (RBCs), which comprise almost 99% of the cells in whole blood, is largely related not only to pathophysiological blood flow but also to the levels of intracellular compounds. Therefore, statistical estimates of the deformability of individual RBCs are of paramount importance in the clinical diagnosis of blood diseases. Although the microscale hydrodynamic interactions of individual RBCs lead to non-Newtonian blood rheology, there is no established method to estimate individual RBC deformability from the rheological data of RBC suspensions, and the possibility of this estimation has not been proven. To address this issue, we conducted an integrated analysis of a model of the rheology of RBC suspensions, coupled with macrorheological data of human RBCs suspended in plasma. Assuming a nonlinear curve of the relative viscosity of the suspensions as a function of the cell volume fraction, the statistical average of the membrane shear elasticity was estimated for individual intact RBCs or hardened RBCs. Both estimated values reproduced well the experimentally observed shear-thinning non-Newtonian behavior in these suspensions. We hereby conclude that our complementary approach makes it possible to estimate the statistical average of individual RBC deformability from macrorheological data obtained with usual rheometric tests.

Numerical simulation of non-Newtonian blood flow in a human arterial bifurcation model

Hemodynamic factors play a role in atherogenesis and the localization of atherosclerotic plaques. The human aorta and coronary arteries are susceptible to arterial disease, and there have been many studies of flows in models of these vessels. Atherosclerosis is a systemic disease occurring in specific sections of the cardiovascular tree such as the carotid and the coronary arteries. This paper aims to simulate the human arterial bifurcation and investigates some hemodynamic parameters as blood propagates from the aortic artery toward the carotid artery. We analyze the velocity, static pressure, shear stress. The simulation results showed disturbed flow patterns, such as flow separation and stagnation, as well as abnormal hemodynamic parameters (HPs) distributions including the low and high wall shear stress (WSS) and oscillation of wall shear stress. Based on our simulating characteristic results, the CFD tools can not only monitor the hemodynamic parameters obviously, but also help to analyze the diagnostic for the treatment of vascular diseases. CFD can be an effective technology for the examination and treatment of patients with failure of blood supply of the head and brain.

Effects of hematocrit and non-Newtonian blood rheology on pulsatile wall shear stress distributions in vascular anomalies: A multiple relaxation time lattice Boltzmann approach

In the present study, we investigate the flow dynamics of non-Newtonian blood, focusing on the distribution of wall shear stress (WSS) and hematocrit levels, which is the volume percentage of red blood cells in whole blood. We analyze these factors under pulsatile conditions, in vascular anomalies such as stent channels and intracranial aneurysms. To achieve this, a three-dimensional computational approach based on the lattice Boltzmann method (LBM) with a multiple relaxation time (MRT) collision operator is employed. To represent the blood's shear-thinning properties, we developed a constitutive model inspired by the Carreau–Yasuda model. This model considers the variability in blood viscosity with shear rate correlated with hematocrit levels based on experimental data documented in the literature. The accuracy of the employed MRT-LBM is demonstrated by the consistency of results with analytical solutions for steady state and experimental data for pulsatile WSS distributions in non-Newtonian and Newtonian fluids. Results indicate that, in areas narrowed by stenosis or expanded by aneurysms, hematocrit levels affect flow dynamics. Higher hematocrit levels intensify pulsatile flow through stenotic regions, increasing WSS cyclic variations. We derived a density distribution function to demonstrate how shear rates vary in vascular anomalies, revealing blood viscosity changes and non-Newtonian properties. These properties complicate flow patterns, resulting in non-linear WSS distributions, which are essential for understanding endothelial cell reactions and disease pathways. Pulsatile blood flow and altered rheological properties due to increased hematocrit affect saccular aneurysm fluid dynamics over time and space, causing vorticities to change shape, size, and intensity.

The influences of artery radii and stenosis severity on the thermal behavior of blood by employing Sisko and Lumen models: Numerical study

Artery stenosis occurs when blood vessels do not supply enough blood and oxygen due to blockage by a fatty mass called plaque. In this work, the influence of stenosis on the Nusselt number (Nu) for non-Newtonian blood flow is studied by the FVM method and using fluent software. Also, the artery is simulated based on the Lumen model. In this research, at first, it is assumed that stenosis severity increases as much as 20 %, 30 %, and 40 % of the internal cross-section area of the artery respectively while the radius is constant, then the stenosis severity is fixed at 40 %, and only radius of artery increases from 0.002 m to 0.0025, 0.0030, and 0.0035 m. The artery wall is affected by constant heat flux and Nusselt numbers in every stage as a significant parameter in each flow are calculated. It should be mentioned that the Nusselt numbers are achieved both in the direction of flow and perpendicular to one. The results show that an increase of stenosis severity from 20 % to 40 % and a decrease of the artery radius between 0.002 and 0.0035 m leads to Nusselt number enhancement due to acceleration of blood flow and increase of heat transfer while the maximum values of Nusselt number remain no change approximately. Therefore, influences of stenosis size on the thermal behavior of blood in the artery are not noticeable, and thermal risks are ignorable.

Non-Newtonian blood flow across stenosed elliptical artery: Case study of nanoparticles for brain disabilities with fuzzy logic

This analysis aimed to explore the blood-based non-Newtonian hybrid nanofluid flow in elliptical stenosed artery with single- and multi-walled carbon nanotubes as nanoparticles. The Carreau fluid model is incorporated to assess the non-Newtonian rheology of blood-based nanofluid for mild stenosis. In particular, the carotid artery is responsible for delivering blood to the brain. If normal blood circulation is disrupted or in the case of severe stenosis, blockage of the carotid artery can lead to the development of brain disability or stroke, which in turn can lead to death. The idealized mathematical equation is transformed into a nondimensional form and solved analytically via the perturbation method through a novel polynomial technique. These analytical solutions are explored and explained graphically. The system’s disorder and variability are assessed by completing an entropy production analysis. The disruption in blood flow due to the presence of nanoparticles causes uncertainty in the flow nature. This uncertainty is dealt with by fuzzy analysis of temperature distribution by accounting for the nanoparticle volume fractions as triangular fuzzy numbers. It is noticed that stenosis shapes and height greatly impact the flow characteristics. The nanoparticles’ percentage in fluid affected the temperature profile. The non-Newtonian characteristics of blood are found to be more dominant along the minor axis, and an effectively higher disorder is produced in this direction. It is observed that the temperature of nanofluid emerged as a triangular fuzzy number of symmetric shape.

Investigation of the size and shape of nano-microcarriers for targeted drug delivery to atherosclerotic plaque in ischemic stroke prevention

Recognizing the significance of drug carriers in the treatment of atherosclerotic plaque is crucial in light of the worldwide repercussions of ischemic stroke. Conservative methodologies, specifically targeted drug delivery, present encouraging substitutes that mitigate the hazards linked to invasive procedures. With the intention of illuminating their considerable significance and prospective benefits, this study examines the impact of the geometry and dimensions of drug-loaded nano-microcarriers on atherosclerotic plaque. The research utilizes a finite element approach to simulate the motion and fluid dynamics of nano-microcarriers loaded with drugs within the carotid arteries. Carriers are available in a variety of shapes and sizes to accommodate patient-specific geometries, pulsatile fluid flow, and non-Newtonian blood properties. Optimization of drug delivery is achieved through the examination of carrier interaction with the inner wall. The results demonstrated that the interaction data between particles and the inner wall of atherosclerotic plaques exhibits micro- and nanoscale patterns that are distinct. Symmetric plaques demonstrate that nanoparticles with a 0.4 shape factor and diameters below 200 nm show the highest interaction rate. Conversely, larger particles (200 and 500 nm) with shape factors of 1 demonstrate comparatively elevated interaction rates. The optimal shape factor for drug-loaded microparticles has been determined to be one, and the number of interactions increases as the diameter of the nanoparticles increases, with a significant increase observed at a shape factor of one. Asymmetric plaques exhibit the maximum interaction rates among particles that have a shape factor of 0.4 and have diameters smaller than 500 µm. The findings establish a foundation for novel therapeutic strategies, establishing nano-microparticles as auspicious contenders for accurate and efficacious drug delivery systems that inhibit plaque proliferation.

An In-Vitro Study On The Carotid Bifurcation And Its Influence On Arterial Haemodynamics With Newtonian And Non-Newtonian Blood Analogs

The carotid artery bifurcation is a region susceptible to atherosclerosis and cardiovascular diseases. The geometry of the bifurcation is individually unique and significant differences have been correlated to both age and gender. Identifying geometric features that produce adverse flow patterns could enable clinicians to make early assessment of an individual’s risk of developing the disease enabling proactive management. Consequently, this study aims to evaluate the influence of the carotid bifurcation angle on arterial haemodynamics using stereoscopic particle image velocimetry. Pulsatile flow conditions were applied to a Newtonian and non-Newtonian blood analog in three compliant, physiologically realistic carotid artery bifurcation phantoms with different bifurcation angles. Results indicate large bifurcation angles can produce adverse flow conditions, increasing size of stagnation regions and promoting plaque development. Additionally, an optimal bifurcation angle could exist that could be considered atheroprotective. Comparison of Newtonian and non-Newtonian blood analogs in one of the geometries show subtle yet significant differences between flow fields, suggesting the shear-thinning behaviour of blood should be carefully considered prior to adopting a Newtonian assumption, even in large vessels.

Haemodynamic effects of non-Newtonian fluid blood on the abdominal aorta before and after double tear rupture

ObjectivesIntimal tears caused by aortic dissection can weaken the arterial wall and lead to aortic aneurysms. However, the effect of different tear states on the blood flow behaviour remains complex. This study uses a novel approach that combines numerical haemodynamic simulation with in vitro experiments to elucidate the effect of arterial dissection rupture on the complex blood flow state within the abdominal aneurysm and the endogenous causes of end-organ malperfusion. Materials and methodsBased on the CT imaging data and clinical physiological parameters, the overall arterial models including aortic dissection and aneurysm with single tear and double tear were established, and the turbulence behaviours and haemodynamic characteristics of arterial dissection and aneurysm under different blood pressures were simulated by using non-Newtonian flow fluids with the pulsatile blood flow rate of the clinical patients as a cycle, and the results of the numerical simulation were verified by in vitro simulation experiments. ResultsHemodynamic simulations revealed that the aneurysm and single-tear false lumen generated a maximum pressure of 320.591 mmHg, 267 % over the 120 mmHg criterion. The pressure differential generates reflux, leading to a WSS of 2247.9 Pa at the TL inlet and blood flow velocities of up to 6.41 m/s inducing extend of the inlet. DTD Medium FL instantaneous WP above 120 mmHg Standard 151 % Additionally, there was 82.5 % higher flow in the right iliac aorta than in the left iliac aorta, which triggered malperfusion. Thrombus was accumulated distal to the tear and turbulence. These results are consistent with the findings of the in vitro experiments. ConclusionsThis study reveals the haemodynamic mechanisms by which aortic dissection induces aortic aneurysms to produce different risk states. This will contribute to in vitro simulation studies as a new fulcrum in the process of moving from numerical simulation to clinical trials.

Hemodynamic coupling between a primary atherosclerotic plaque and subsequent secondary lesions

Atherosclerosis is one of the most common diseases of the arterial tree, especially in the coronary arteries. Stenoses exceeding 50% area reduction are shown to alternate the downstream coronary flow, and hemodynamics will lead to further atherogenesis. Clinical evidence also confirms that vascular stenoses are not stagnant since they are usually associated with downstream lesions. In this study, it is hypothesized that the formation of secondary plaques, or aneurysms downstream of a primary stenosis, compensates for the abnormal ranges of hemodynamic forces caused by the primary stenosis. An experimental setup captured the hemodynamics of non-Newtonian blood flow in three-dimensional (3D) printed phantoms of coronary arteries with various sequences of lesions. Then, based on the collected data, in silico models of these lesions were simulated using computational fluid dynamics. For the proposed cases, time-averaged wall shear stress, velocity profile, oscillatory shear index, and relative residence time were extracted at the plaque side and the plaque front walls and compared to the reference model with only the primary plaque. The secondary plaque postulated the abnormal hemodynamic conditions to its downstream, which implies endothelial activation and onset of further pathologic events. However, the secondary aneurysm restored flow conditions to normal after its distal shoulder, preventing more damage to the endothelium. Examined angiograms of patients with developed atherosclerotic lesions unveiled that a sequence of plaques is formed over time, and most interestingly, the series stopped after the formation of an aneurysm.

A comparative study of Newtonian and non-Newtonian blood flow through Bi-Leaflet Mechanical Heart Valve

The present study examines flow through Bi-Leaflet Mechanical Heart Valves (BMHV) at physiological conditions considering both Newtonian and non-Newtonian fluid models for blood rheology. It is well known that the non-Newtonian effects of blood are pronounced in small diameter arteries. Most of the earlier works on Mechanical Heart Valves (MHV) have considered blood as a Newtonian fluid as the flow involves large-diameter artery such as the aorta. In this work, we have reported the predicted parameters, such as leaflet kinematics, vortex structures, wall shear stress, and blood damage index for both blood models. It is found that the leaflet attributes smaller asynchronous motion in the case of non-Newtonian Carreau fluid model with slightly reduced angular velocity compared to the Newtonian assumption. Predictions on the blood damage index suggest a 21% higher damage while using non-Newtonian model than Newtonian model, which may be attributed to higher levels of mechanical stress within the fluid. However, vortex structures, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) are found to be similar in predictions using both the fluid models. We have used an in-house sharp interface immersed boundary method with fluid–structure interaction to simulate the coupled action of moving valves and pulsatile blood flow. Our findings suggest that the general consensus of using Newtonian model in large arteries may not be appropriate for prediction of leaflet kinematics and blood damage index in Mechanical heart valves.

Endovascular Treatment of Intracranial Aneurysm: The Importance of the Rheological Model in Blood Flow Simulations.

Hemodynamics in intracranial aneurysm strongly depends on the non-Newtonian blood behavior due to the large number of suspended cells and the ability of red blood cells to deform and aggregate. However, most numerical investigations on intracranial hemodynamics adopt the Newtonian hypothesis to model blood flow and predict aneurysm occlusion. The aim of this study was to analyze the effect of the blood rheological model on the hemodynamics of intracranial aneurysms in the presence or absence of endovascular treatment. A numerical investigation was performed under pulsatile flow conditions in a patient-specific aneurysm with and without the insertion of an appropriately reconstructed flow diverter stent (FDS). The numerical simulations were performed using Newtonian and non-Newtonian assumptions for blood rheology. In all cases, FDS placement reduced the intra-aneurysmal velocity and increased the relative residence time (RRT) on the aneurysmal wall, indicating progressive thrombus formation and aneurysm occlusion. However, the Newtonian model largely overestimated RRT values and consequent aneurysm healing with respect to the non-Newtonian models. Due to the non-Newtonian blood properties and the large discrepancy between Newtonian and non-Newtonian simulations, the Newtonian hypothesis should not be used in the study of the hemodynamics of intracranial aneurysm, especially in the presence of endovascular treatment.

Enhancing magnetic drug targeting efficiency through computational analysis: Investigating Particle-RBC interaction and non-newtonian blood behavior

Cancer stands as a foremost global mortality determinant, characterized by a persistent deficit in therapeutic modalities capable of reliably and efficiently conveying anti-cancer pharmaceutical agents to profound tissue loci. Within this context, magnetic drug targeting (MDT) has emerged as an innovative approach to cancer management, offering the promise of minimal adverse effects. Accordingly, the current investigation endeavors to evaluate the capture efficacy (CE) of drug-loaded nanoparticles under the influence of an external magnetic field. To this end, a cylindrical neodymium magnet (NdFeB) is employed as the magnetic source. The finite element method (FEM) was utilized to solve the governing equations. The effect of several parameters, including particle diameter, drag force, blood properties, magnetic field intensity, blood’s non-Newtonian behavior, and particle-RBC interaction on the CE of nanoparticles has been investigated. Simultaneous effect of interaction forces and non-Newtonian behavior of blood on the capturing nanoparticles at the tumor site is considered as the novelty of the present work. Taking into account these two parameters will provide more realistic results. Finding showed that the magnetic field intensity and particles’ diameter positively affect the nanoparticles’ CE. For example, by increasing particle diameter from 250 nm to 1500 nm, the CE is increased from 22 % to 53 %, respectively. In addition, it was revealed that consideration of the particle-red blood cell (RBC) interaction, on average, causes a decrease in the CE of nanoparticles by up to 20 %. Regarding the non-Newtonian behavior of blood, it was found that considering blood as non-Newtonian fluid would decrease, on average, 25 % of CE of nanoparticles compared to Newtonian fluid. Results revealed that simultaneous considering the non-Newtonian behavior of blood and interaction forces significantly affect the CE of nanoparticles.

THE ANALYSIS OF THE FLOW OF BLOOD IN A STENOSED ARTERY THROUGH SIMULATION: A COMPARISON AMONG VARIOUS NON-NEWTONIAN MODELS

This paper focuses on the dual quality of blood, Newtonian and non-Newtonian, in particular by exploring the energy curves. Careful investigation of the dual property of blood has been made by considering two different geometries to represent a stenosed arterial segment. We present a cautious assessment of non-Newtonian blood rheology impacts in arterial stream simulations by coupling the Newtonian and non-Newtonian models. The flow of energy through the two flow dimensions is meticulously investigated using velocity (kinetic energy), pressure, and wall shear stress (pressure energy). Besides, the proper implementation of an interface boundary condition (IBC) was emphasized to ensure consistency with the flow conditions downstream of a backward-facing step. The integration of the Newtonian and non-Newtonian models adjoins the novelty of the current research. The energy curves are obtained by implementing five different non-Newtonian models to designate a suitable non-Newtonian model for blood flow investigations. The combination of the non-Newtonian models enforced in this research is novel and particular attention is paid to the energy curves obtained. The conclusion was to elect the Carreau model as a suitable non-Newtonian rheological model for the blood flow study. This study was able to finalize the fact that the coupling of Newtonian and non-Newtonian models is necessary to obtain accurate results. For the sinusoidal waveform considered for the velocity, Carreau and the Power law models yield better results, eliminating the other non-Newtonian models from the list. With a better inlet condition imposed in the form of the Fourier series for pressure and velocity, the Carreau model yields the best results.

Modeling analysis of pulsatile non-Newtonian blood flow in a renal bifurcated artery with stenosis

A transient transport flow model is adopted in a renal bifurcated artery with different stenosis cases to examine the flow phenomena when the non-Newtonian blood flow regime within the three-dimensional space domain is chosen as a pulsatile nature. The nonlinear governing equations are solved using the Finite Element Method with suitable initial-boundary conditions. During numerical computation, distinct hemodynamic parameters including Wall shear stress, Reynolds number, power law index are evaluated based on different stenosis severities (0%, 25%, and 50%) and stenosis lengths (0mm, 0.5mm, and 1mm). For 0%, 25%, and 50% stenosis, the approximate values of velocity and pressure profiles are estimated at t = 5s at various positions, and achieved the highest velocities that were around 0.07m/s, 0.08m/s, and 0.13m/s respectively. The unsteady response of the stress due to stenosis-induced shear on the outside wall is described as a result of stenosis at t = 0.1s, 0.2s, 5s. The flow is severely restricted by constriction, which increases wall movement and produces stress, depending on the amount of stenosis. As pulsatile flow time increases due to the presence of stenosis, the wall shear stress decreases gradually. The impact of Reynolds numbers on pressure profiles and velocity profiles are displayed for Re = 100, 300, 500, and 700, and found that both velocity and pressure outlines increase significantly. In order to identify the flow phenomena, the influences of the power law index for n = 0.1, 0.3568, 0.5 are presented on the velocity and pressure profiles. Shear-thinning flow occurs for 0<n<1, pseudoplastic flow occurs for n = 0.1 and Bingham plastic flow occurs for n = 0.5. The modeling investigations of blood flow via arteries could assist in the diagnosis and treatment of arterial illnesses; as well as expand the knowledge about cardiovascular physiology and lead the development of revolutionary medical interventions to enhance patient treatment outcomes.

Thermal Analysis of a Casson Boundary Layer Flow over a Penetrable Stretching Porous Wedge

This work aims to analyze the Casson thermal boundary layer flow over an expanding wedge in a porous medium with convective boundary conditions and ohmic heating. Moreover, the effects of porosity and viscous dissipation are studied in detail and included in the analysis. The importance of this study is due to its applications in biomedical engineering where the analysis of behavior of non-Newtonian blood flow in arteries and veins is desired. Within the context of blood flow, it is also applicable to many other fields, for instance, radiative therapy, MHD generators, soil machines, melt-spinning, and insulation processes. The modeled problem is a set of PDEs, which is nondimensionalized to derive a nonlinear boundary value problem (BVP). The obtained BVP is solved using the shooting technique, endowed with the order four Runge-Kutta and Newton methods. The impact of different parameters on the momentum and temperature fields is investigated along with two important parameters of physical significance, i.e., the Nusselt number and the surface drag force. Results are validated, and an excellent agreement is seen for the parameters of interest using MATLAB built-in function bvp4c. A significant finding is that by increasing the Casson liquid parameter, the velocity decreases as the wedge expands quicker than the free stream velocity at R=2. However, the velocity increases for the case when R=0.1. A decrease in the Darcy number increases the temperature profile. Furthermore, the convective parameter accelerated the heat transmission rate, and a rise in the Prandtl number thickens the thermal boundary layer. The findings of this investigation contribute to problems in fluid dynamics and heat transfer that involve studying the behavior of a non-Newtonian fluid with Casson rheological properties near a solid porous wedge surface.

Entropy-based analysis of hemodynamics in elliptical arterial flows with non-Newtonian Rabinowitsch fluid

This research concerns examining the non-Newtonian blood flow behavior through an artery of elliptic cross-section, affected by several stenoses. The Rabinowitsch fluid model is used to investigate the non-Newtonian behavior of the blood for uniform and nonuniform shapes of stenosis. The mathematical equations have been converted into a dimensionless form, and their nonlinearity is reduced by applying the assumptions of mild stenosis. The resulting differential equations are solved by using analytical techniques. A new polynomial of degree eight is introduced to complete the solutions of mathematical equations. The entropy generation is studied mathematically to analyze the irreversibility effects. The detailed graphical examination delineates the physical aspects of mathematical results. The flow velocity is higher for uniform shape than for nonuniform stenosis. The rising percentage of stenosis significantly enhances the flow velocity of the stenotic region. The entropy is enormous near the stenotic wall and has small values near the centerline, which assures the smooth flow in this region. Further, the streamlines are plotted to find the position of stenosis and assess the flow nature for the growing height of stenosis and rising flow rate.

Pulsatile pressure-driven non-Newtonian blood flow through a porous stenotic artery: A computational analysis

Blood flow through a narrowed artery, such as those caused by plaque buildup, can lead to various cardiovascular diseases. Therefore, studying this phenomenon is essential for developing better treatments and understanding the underlying mechanisms. In this study, a mathematical model is developed to simulate blood flow through stenotic arteries with porous walls. The familiar Navier-Stokes equations are executed to simulate flow, whereas the Carreau fluid model is employed to quantify blood rheology. This model illustrates both Newtonian and non-Newtonian characteristics depending on the shear rate. Other than that, the blood vessel is assumed to have a moderate level of stenosis with porous saturated walls. The solution of the governed partial differential equations is carried out using a finite difference scheme. Our research addresses the impacts of permeability and rheological parameters, stenosis size, Brinkman number, and Prandtl number on blood velocity, flow rate, resistance to flow, wall shear stress, and temperature distribution. The findings demonstrate that while flow resistance reduces, the velocity, shear stress, and flow rate increase with high permeability values. Conversely, as the stenosis amplitude increases, the magnitude of wall shear stresses, velocity, and flow rates decrease. In addition, blood rheology also has the potential to transfigure the aforementioned factors. We also found that the temperature distribution increases with the Brinkman number, stenosis size, permeability, and power law exponent. It drives down, however, by raising the values of Weissenberg number and Prandtl number. Collectively, our findings contribute to a better understanding of the complicated phenomena of blood flow in stenotic vessels with porous saturated walls. The findings of this study may be valuable in establishing improved therapies for cardiovascular disorders and formulating more precise mathematical models to forecast blood flow in vivo.