Blood Flow Behavior Research Articles

Numerical Modeling and Simulation of Blood Flow in a Rat Kidney: Coupling of the Myogenic Response and the Vascular Structure

A numerical simulation was carried out to investigate the blood flow behavior (i.e., flow rate and pressure) and coupling of a renal vascular network and the myogenic response to various conditions. A vascular segment and an entire kidney vascular network were modeled by assuming one single vessel as a straight pipe whose diameter was determined by Murray’s law. The myogenic response was tested on individual AA (afferent artery)–GC (glomerular capillaries)–EA (efferent artery) systems, thereby regulating blood flow throughout the vascular network. Blood flow in the vascular structure was calculated by network analysis based on Hagen–Poiseuille’s law to various boundary conditions. Simulation results demonstrated that, in the vascular segment, the inlet pressure Pinlet and the vascular structure act together on the myogenic response of each individual AA–GC–EA subsystem, such that the early-branching subsystems in the vascular network reached the well-regulated state first, with an interval of the inlet as Pinlet = 10.5–21.0 kPa, whereas the one that branched last exhibited a later interval with Pinlet = 13.0–24.0 kPa. In the entire vascular network, in contrast to the Pinlet interval (13.0–20.0 kPa) of the unified well-regulated state for all AA–GC–EA subsystems of the symmetric model, the asymmetric model exhibited the differences among subsystems with Pinlet ranging from 12.0–17.0 to 16.0–20.0 kPa, eventually achieving a well-regulated state of 13.0–18.5 kPa for the entire kidney. Furthermore, when Pinlet continued to rise (e.g., 21.0 kPa) beyond the vasoconstriction range of the myogenic response, high glomerular pressure was also related to vascular structure, where PGC of early-branching subsystems was 9.0 kPa and of late-branching one was 7.5 kPa. These findings demonstrate how the myogenic response regulates renal blood flow in vascular network system that comprises a large number of vessel elements.

Application of Biomagnetic Fluid Dynamics modeling for simulation of flow with magnetic particles and variable fluid properties over a stretching cylinder

An incompressible, electrically conducting Biomagnetic Fluid Dynamics (BFD) flow—namely the flow of blood with magnetic particles through a two-dimensional stretching cylinder under the influence of a magnetic dipole—is numerically and theoretically investigated in the present study. Herein, fluid viscosity and thermal conductivity are supposed to vary as an inverse function and as linear functions of temperature, respectively. This study involves two areas of analysis, namely magnetohydrodynamics (MHD) and ferrohydrodynamics (FHD). The basic blood flow features when magnetic particles are added to blood, as well as those of pure blood are discussed. Using a similarity approach, the governing system of partial differential equations are converted into a system of ordinary differential equations which are solved numerically by considering an efficient technique based on a common finite differences method, consisting of central differencing, tridiagonal matrix manipulation and an iterative procedure. The significant effects of various physical non-dimensional parameters concerning the axial velocity, temperature, skin friction coefficient and rate of heat transfer are demonstrated graphically. The obtained results reveal that with increasing values of the ferromagnetic interaction parameter, the magnetic field parameter, the thermal conductivity parameter and the viscosity variation parameter, fluid (blood-Fe3O4) velocity is reduced, whereas both axial velocity and temperature are enhanced for the curvature parameter. Both the skin friction coefficient and the rate of heat transfer decline with rising values of the thermal conductivity parameter. To make the results physically reliable, a temporal stability analysis is also provided in this study. Finally, the accuracy of the applied numerical technique is validated with existing published literature for some limiting cases, and the results are found to be in excellent agreement. The present outcomes disclose that the behavior of blood flow can be controlled by employing a strong magnetic field. It is hoped that such kind of results will be useful in medical sector especially in MRI, magnetic drug targeting and magnetic hyperthermia treatments.

Heat Transfer Analysis and Effects of (Silver and Gold) Nanoparticles on Blood Flow Inside Arterial Stenosis

The current investigation was based on a simulation employing CFD in COMSOL Multiphysics. The base fluid that was used in this simulation was blood. The flow was considered as a laminar, unsteady and incompressible Newtonian fluid, and the Newtonian nature of blood is acceptable at high shear rate. The behavior of blood flow was analyzed with the objective of obtaining pressure, temperature and velocity effects through an arterial stenosis. Two types of nanoparticles were used in this work: silver (Ag) and gold (Au). The equations of mass, momentum and energy were solved by utilizing the CFD technique. A fine element size mesh was generated through COMSOL. The results of this analysis show that velocity changes through confined parts of the artery, the velocity in a diseased region is higher and the velocity decreases before and after the stenotic region. In the heat transfer feature, the upper and lower boundary temperature was set to 24.85 °C and 27.35 °C, respectively. The nanoparticles affected the physical properties of blood, such as thermal conductivity, density, dynamic viscosity and specific heat. The addition of gold and silver nanoparticles prevented overheating because both nanoparticles have a high thermal conductivity, which has a principal role in dissipating temperature quickly. Nusselt number variations were also calculated and the results show that the curve decreases inside the stenosis. It could be concluded that the streamlines show abnormal behavior and recirculation occurs just after the stenosed area at t = 0.7 s and 1 s. These results will help greatly in the treatment of stenosed arteries.

The thermal behavior of blood flow in the arteries with various radii and various stenosis angles using non-Newtonian Sisko model

In this work, the FVM method is employed to simulate blood flow behavior within stenosis arteries based on the non-Newtonian Sisko model by using UDF in Fluent. Stenosis is simulated in cone geometry, and influences of different angles of stenosis with different artery radii are studied on the Nusselt number and temperature of blood flow. It is observed that with increasing angles of stenosis and reducing internal radius, the artery is narrowed, which results in enhancement of Nusselt number of blood flow. Thus, the temperature of blood flow is reduced. Also, applying heat fluxes of q“ = 400 W/m2, q” = 800 W/m2, and q“ = 1000 W/m2 prepare temperature enhancement as much as 0.44 K, 0.89 K, and 1.15 K respectively which are important from a medical viewpoint. The maximum temperature is reported as much as 38.2 °C by applying heat flux of q” = 1000 W/m2, which is noticeable for the human body healthy, especially for the function of enzymes and other proteins of the body. Also, with increasing angles of stenosis and reducing internal radius, the artery is tightened and velocity of blood fluid is enhanced which affects blood circulation between tissues and the oxygenation process, temperature variation, and heat transfer alteration of blood flow within the human body. In reality, circulation of blood transfers heat between tissues, and the dimensions of the blood vessels are various, whenever more blood is needed in some vessels of the body due to more activity, these blood vessels expand to supply the required blood while other vessels tight to compensate it. Therefore, present mechanical research is applicable for medical science especially in surgical widening of a blocked or narrowed blood vessel.

Analysis of blood flow through curved artery with mild stenosis

Building-up of plaque narrows arteries, decreasing blood flow to the heart, causing chest pain, shortness of breath, or other coronary artery disease signs and symptoms. Implementing Navier–Stokes equations in a cylindrical coordinate system and assuming axial symmetry under laminar flow conditions, the study has been conducted on the two aspects of blood flow dynamics viz., velocity profile and volumetric flow rate of blood around curved stenosis with a variation of curvature of the artery and the stenosis thickness. The blood flow behavior taking different values for the viscosity coefficient has been also studied.

Performance Analysis of Magnetic Nanoparticles during Targeted Drug Delivery: Application of OHAM

In recent years, the emergence of nanotechnology experienced incredible development in the field of medical sciences. During the past decade, investigating the characteristics of nanoparticles during fluid flow has been one of the intriguing issues. Nanoparticle distribution and uniformity have emerged as substantial criteria in both medical and engineering applications. Adverse effects of chemotherapy on healthy tissues are known to be a significant concern during cancer therapy. A novel treatment method of magnetic drug targeting (MDT) has emerged as a promising topical cancer treatment along with some attractive advantages of improving efficacy, fewer side effects, and reduce drug dose. During magnetic drug targeting, the appropriate movement of nanoparticles (magnetic) as carriers is essential for the therapeutic process in the blood clot removal, infection treatment, and tumor cell treatment. In this study, we have numerically investigated the behavior of an unsteady blood flow infused with magnetic nanoparticles during MDT under the influence of a uniform external magnetic field in a micro-tube. An optimal homotopy asymptotic method (OHAM) is employed to compute the governing equation for unsteady electromagnetohydrodynamics flow. The influence of Hartmann number (Ha), particle mass parameter (G), particle concentration parameter (R), and electro-osmotic parameter (k) is investigated on the velocity of magnetic nanoparticles and blood flow. Results obtained show that the electro-osmotic parameter, along with Hartmann’s number, dramatically affects the velocity of magnetic nanoparticles, blood flow velocity, and flow rate. Moreover, results also reveal that at a higher Hartman number, homogeneity in nanoparticles distribution improved considerably. The particle concentration and mass parameters effectively influence the capturing effect on nanoparticles in the blood flow using a micro-tube for magnetic drug targeting. Lastly, investigation also indicates that the OHAM analysis is efficient and quick to handle the system of nonlinear equations.

A particulate blood analogue based on artificial viscoelastic blood plasma and RBC-like microparticles at a concentration matching the human haematocrit.

There has been enormous interest in the production of fluids with rheological properties similar to those of real blood over the last few years. Application fields range from biomicrofluidics (microscale) to forensic science (macroscale). The inclusion of flexible microparticles in blood analogue fluids has been demonstrated to be essential in order to reproduce the behaviour of blood flow in these fields. Here, we describe a protocol to produce a whole human blood analogue composed of a proposed plasma analogue and flexible spherical microparticles that mimic the key structural attributes of RBCs (size and mechanical properties), at a concentration matching the human haematocrit (∼42% by volume). Polydimethylsiloxane (PDMS) flexible microparticles were used to mimic RBCs, whose capability to deform is tunable by means of the mixing ratio of the PDMS precursor. Their flow through glass micronozzles allowed us to find the appropriate mixing ratio of PDMS to have approximately the same Young's modulus (E) as that exhibited by real RBCs. Shear and extensional rheology and microrheology techniques were used to match the properties exhibited by human plasma and whole blood at body temperature (37 °C). Finally, we study the flow of our proposed fluid through a microfluidic channel, showing the in vitro reproduction of the multiphase flow effects taking place in the human microcirculatory system, such as the cell-free layer (CFL) and the Fåhræus-Lindqvist effect. A macroscale application in the field of forensic science is also presented, concerning the impact of our blood analogue droplets on a solid surface for bloodstain pattern analysis.

Simultaneous quantification of blood rheology and oxygen saturation to evaluate affinity-modifying therapies in sickle cell disease.

Sickle cell blood demonstrates oxygen-dependent flow behavior as a result of HbS polymerization during hypoxia, and these rheological changes provide a biophysical metric that can be used to quantify the pathological behavior of the blood. Relating these rheological changes directly to hemoglobin oxygen saturation would improve our understanding of SCD pathogenesis and the potential effects of therapeutic drugs. Towards this end, we have developed a microfluidic platform capable of spectrophotometric quantification of Hb-O2 saturation and simultaneous evaluation of the accompanying rheological changes in SCD blood flow. We demonstrated the ability to measure changes in Hb-O2 affinity and a restoration of oxygen-independent blood flow behavior after incubation with voxelotor, an oxygen affinity modifying drug approved for use in SCD. We also identified regimes in Hb-O2 saturation where the effects of HbS polymerization begin to take effect in contributing to pathological flow behavior, independent of voxelotor treatment. In contrast, incubation with voxelotor recovered oxygen-dependent blood flow over a range of PO2, providing a framework for understanding voxelotor's therapeutic effect in lowering the PO2 at which the requisite Hb-O2 saturation is reached to observe pathological blood flow. These results help explain the mechanistic effects of voxelotor and show the potential of this platform to identify affinity-modifying compounds and evaluate their therapeutic effect on blood flow.

Impact of small fractions of abnormal erythrocytes on blood rheology.

Red blood cell (RBC) populations are inherently heterogeneous, given mature RBC lack the transcriptional machinery to re-synthesize proteins affected during in vivo aging. Clearance of older, less functional cells thus aids in maintaining consistent hemorheological properties. Scenarios occur, however, where portions of mechanically impaired RBC are re-introduced into blood (e.g., damaged from circulatory support, blood transfusion) and may alter whole blood fluid behavior. Given such perturbations are associated with poor clinical outcomes, determining the tolerable level of abnormal RBC in blood is valuable. Thus, the current study aimed to define the critical threshold of blood fluid properties to re-infused physically-impaired RBC. Cell mechanics of RBC were impaired through membrane cross-linking (glutaraldehyde) or intracellular oxidation (phenazine methosulfate). Mechanically impaired RBC were progressively re-introduced into the native cell population. Negative alterations of cellular deformability and high shear blood viscosity were observed following additions of only 1-5% rigidified RBC. Low-shear blood viscosity was conversely decreased following addition of glutaraldehyde-treated cells; high-resolution microscopy of these mixed cell populations revealed decreased capacity to form reversible aggregates and decreased aggregate size. Mixed RBC populations, when exposed to supraphysiological shear, presented with compounded mechanical impairment. Collectively, key determinants of blood flow behavior are sensitive to mechanical perturbations in RBC, even when only 1-5% of the cell population is affected. Given this fraction is well-below the volume of rigidified RBC introduced during circulatory support or transfusion practice, it is plausible that some adverse events following surgery and/or transfusion may be related to impaired blood fluidity.

Heat transfer and hemodynamic analysis of systolic and diastolic hypertension on abdominal aortic thrombosis

Thrombosis is a blood clot formed in the vascular system and obstructs blood flow by reducing the cross-sectional area of blood vessels, posing a great threat to human health. Computational hemodynamics is a well-known method used for numerical simulation of blood flow behaviour. Diastolic and systolic hypertension can be investigated using the FVM and SIMPLE scheme for pressure-velocity coupling. Thanks to the utilization of MRI and DICOM, there is an acceptable 3D geometric accuracy based on which the geometry was constructed. In this study, a numerical study was performed on the behavior of the non-Newtonian blood flow in the abdominal aorta with different shapes of thrombus in three thermal fluxes generated by the body (i.e., running, sleeping, and standing). So, Blood flow behavior in three thrombus shapes of circular, rectangular, and triangular was also explored. This paper reported the influence of dimensionless numbers, including pressure drop, heat transfer coefficient, temperature, and Average Wall Shear Stress (AWSS). Based on clinical data, velocities in the abdominal aorta range from 1 to 1.2 m s−1, and blood temperature is 309.55 K. The results showed that the triangular thrombus was the most effective.

Model-Predicted Clinical Factors Impacting Patient-Specific Response of Sickle Cells to Voxelotor in a Microfluidic Platform

Background: Sickle cell disease (SCD) is a group of genetic disorders in which sickle hemoglobin polymerizes under deoxygenation, altering red blood cell (RBC) morphology and behavior. The properties of sickle RBCs contribute to increased viscosity of blood and occurrence of vaso-occlusions, a major aspect of SCD pathophysiology. Voxelotor is a novel FDA-approved treatment for SCD which modulates hemoglobin O 2 affinity, and while its known mechanism inhibits sickle polymerization, the impact on other aspects of SCD pathophysiology remain unknown. Thus, despite the new treatment option, highly variable clinical manifestation continues to be a hallmark of sickle cell and there is consequently a need to optimize the use of current therapies based on patient-specific factors. In this work, we leverage datasets generated from a unique microfluidic assay that measures blood flow behavior under varying oxygen tension in conjunction with novel statistical approaches to model and assess sources of variability in sickle blood flow response to voxelotor.Methods: RBCs from patients with SCD (n=28) were treated with voxelotor at 500 uM concentration. Treated samples and untreated controls were perfused through a microfluidic platform that dynamically modulates oxygen tension and measures flow velocity (Wood et al, 2012; Valdez et al, 2019). The area between curves (ABC) of the normalized velocity across the range of oxygen tension between treated and control conditions was calculated to quantify the effect of voxelotor for each sample (figure 1). A paired t-test was used to assess the difference in response between treated and untreated samples. Where available, clinical data including the hemoglobin fractions and complete blood count (CBC) were collected for each sample as predictor variables, and partial least squares regression (PLSR) modeling was used to assess the correlation of predictors and responses.Results: Voxelotor increased the velocity ABC from untreated to treated conditions (p<.0001). We observed that there were differences in response for velocity ABC between sickle cell genotypes (figure 2). Thus, generating separate PLSR models for distinct SCD genotypes revealed differences in sets of clinical factors that explained the most variance in response to voxelotor treatment. A 2-component model was constructed for the HbSC samples (n=6) that best explained variance in the data and had good predictive abilities (R 2X=.69, R 2Y=.97, Q 2=.74). Within this subset, clustering of variables related to hemolysis and inflammation were observed (figure 3). An equivalent model constructed for the HbSS samples (n=15) characterized the predictor variables but lacked predictive power of the response (R 2X=.74, R 2Y=.25, Q 2=.-0.21). Response to voxelotor for this model was most strongly correlated with HbA. Due to low sample size (n=2 samples with full set of predictors), predictive modeling was not performed for HbSβ 0 samples, however, these samples responded the least to voxelotor treatment.Conclusions: Our analysis quantified patient-specific differences in the blood flow response to voxelotor, showing a wide variability in response despite treatment by the same drug concentration. Genotype-specific multivariable models that take into account easily measurable clinical variables such as the CBC have the potential to explain the variability in patient response to voxelotor treatment. In HbSC samples, the WBC, platelet, and reticulocyte counts were highly correlated and strong predictors of response to voxelotor, which may point to markers of hemolysis and inflammation being useful in determining patients that can be optimally treated with this drug. In HbSS, response to voxelotor was mainly inversely correlated with HbA levels, which is a surrogate marker for blood transfusions, indicating that the effect of voxelotor is lessened for patients who are receiving transfusions. However, the low R2Y of this model highlights the clinical variability in this SCD genotype and consequent need for additional biomarkers of disease severity. In conclusion, our hybrid experimental-computational approach is able to identify clinical factors that highly impact the response of patient blood samples to treatment with voxelotor for HbSC patients, and highlights the need for precision therapy recommendations in SCD. [Display omitted] DisclosuresLam: Sanguina, Inc.: Current holder of individual stocks in a privately-held company. Kemp: Parthenon Therapeutics: Membership on an entity's Board of Directors or advisory committees.

The Role of Gray-Scale Ultrasound in the Diagnosis of Postnatal Testicular Torsion in Children

Testicular torsion is a severe variant of postnatal gonad pathology in children. The speed of development of irreversible ischemic disorders determines not only the medical, but also the social significance of the problem and determines the need for accurate and rapid diagnosis and prompt provision of adequate care to the patient. The only objective method for diagnosing testicular torsion in children is ultrasound. At the same time, the characteristics of the child’s body: the small size of the object of study, low rates of intratesticular blood flow and restless behavior during the study sharply reduce the diagnostic value of the Doppler study or make it technically impossible. Thus, seroshkal ultrasound is the first stage of diagnosis of this complex emergency pathology, based on the results of which it is possible to diagnose testicular torsion with great accuracy. The publication summarizes our own experience of 110 echographic observations of postnatal testicular torsion in children older than 2 months, all cases were verified intraoperatively. A quantitative method for estimating the deformity of a twisted testicle is proposed and its statistical reliability is proved. The options presented for gray-scale changes in the structure of damaged gonads and determined their prognostic significance. The publication contains a review of the literature and is extensively illustrated.

Effect of real and whole blood rheology on flow through an axisymmetric stenosed artery

This study presents an extensive numerical investigation on the flow phenomena of a blood analogous fluid through an axisymmetric stenosed artery under both steady and pulsatile flow conditions. Most of the previous investigations, carried out for this benchmark problem, used either a simple Newtonian fluid model or a generalized Newtonian (GNF) fluid model like the power-law or Bingham plastic fluid model to represent the rheological behaviour of blood. However, many prior rheological studies showed that the real and whole blood exhibits both the shear-thinning and viscoelastic properties. In this study, for the first time, a multi-mode sPTT (simplified Phan-Thein-Tanner) model is used to carry out the numerical computation, which accounts for both the shear-thinning and viscoelastic rheological properties of blood. Additionally, a realistic set of viscoelastic model parameters, obtained by fitting the response of real and whole blood in standard viscometric flows, is used in this study. An excellent agreement is seen between the experimentally determined apparent viscosity (in simple shear flows) of blood with that predicted by the present viscoelastic model and other prior models developed for blood. Therefore, we believe that this study presents more accurate and realistic numerical results for the flow of blood through a stenosed artery than that presented by the previous studies in the literature. A simple Newtonian fluid model is also used in the present analysis to compare and show how the flow behavior of blood can be influenced by its complex rheological properties under otherwise identical conditions. We find a significant difference in the flow characteristics (in terms of the streamline profiles, velocity magnitude, pressure drop, etc.) obtained with the Newtonian and viscoelastic fluid models. For instance, the velocity gradient is seen to be large near the artery wall for the viscoelastic fluid model than that seen for the Newtonian model; whereas, a reverse trend is seen for the pressure drop across the stenosis. Furthermore, we find that the flow dynamics is strongly modulated by the stenosis geometry, Reynolds number and flow types, i.e., whether it is steady or pulsatile.

Blood Flow with Multiple Stenoses in a Force Field

In the present manuscript, a mathematical model of steady and incompressible Casson fluid in a non-uniform tube having many stenoses in the presence of a force field is analyzed. Using mild stenosis approximation and appropriate boundary conditions, analytical expressions for velocity, pressure drop, impedance, and wall share stress have been computed due to their importance in the rheology of blood. The Casson fluid is used to depict the behavior of blood flow. The effects of different physical constraints on resistance to the flow and wall shear stress of the fluid are examined. The study ascertains that resistance to the flow and wall shear stress is maximum at duck of stenosis. It is also explored that an increase in the size of the stenosis in the artery affects the normal flow of the blood through vessels in the heart, body, and brain and this may lead to major cardiac disease problems like stroke, heart attack, etc.

Virtual Reality Visualization of CFD Simulated Blood Flow in Cerebral Aneurysms Treated with Flow Diverter Stents

Virtual reality (VR) has the potential to be a powerful tool for the visualization of simulated blood flow in cerebral aneurysms. This paper presents our study aimed at developing the VR visualization of computational fluid dynamics (CFD) simulations of cerebral aneurysms treated with flow-diverting (FD) stents. First, a spherical sidewall aneurysm located at a simplified internal carotid artery was considered for investigating the impact of stent deployment and positioning on the corresponding spatially time-varying blood flow behavior. The three-dimensional unsteady blood flow over a cardiac cycle was simulated numerically using the finite volume method, and the distributions of hemodynamic parameters inside the aneurysm sac, and on its wall, were presented with and without stent cases. Two stent positions, with and without a gap between the artery wall and stent, were considered to show the influence of correct stent position on aneurysm treatment. Second, a straightforward workflow was developed to import, process, and visualize the CFD analysis data in a VR environment by using open-source software with a high resolution. The Unity3D engine was used for displaying the processed animations in a VR environment operated on a head-mounted display (HMD). The refining process of each frame of time-varying CFD data was automated. The animated flow elements rendered in the VR environment were velocity vectors, velocity contours, streamlines, particle traces, and point clouds. CFD results showed that proper stenting facilitates thrombosis and occlusion of the aneurysm by modification of the flow patterns, which leads to lower inflow jet velocities into the aneurysm, longer turnover time, lower aneurysm-averaged kinetic energy, and lower wall shear stress. Additionally, the results indicated that a gap between the stent and the parent artery may lead to undesirable hemodynamic alterations. The VR visualization illustrated that the recognition of the potential in danger regions of aneurysms and the evaluation of the performance of FD stents in aneurysm treatment can be conducted without the need for several slices through the parent artery and aneurysm, as is required for traditional postprocessing methods. Through VR visualization, the details of the simulation results become readily available by navigating in the 3D animated flow elements using a high-degree-of-freedom headset.

Mathematical Analysis of Unsteady Solute Dispersion with Chemical Reaction Through a Stenosed Artery

One major kind of arterial disease in blood flow that attracted many researchers is arterial stenosis. Arterial stenosis occurs when a lumen of artery is narrowed by the accumulation of fats, cholesterols and lipids plaques at the inner layer of the wall of an artery. To treat this arterial disease, the drug (solute) is injected into the blood vessels. Injection of the drug into the blood vessel cause the occurrence of chemical reaction between the drug and blood proteins and it affects the effectiveness of the solute transportation in blood flow. Hence, this study examines the unsteady dispersion of solute with the influence of chemical reaction and stenosis height through a very narrow artery with a cosine-curved stenosis. The blood is treating as Herschel-Bulkley (H-B) fluid. The momentum and constitutive equations are solved analytically to gain velocity of H-B blood flow. The convective-diffusion equation is solved by applying the generalized dispersion model to gain the dispersion function of solute. The influence of chemical reaction, power-law index, plug flow radius and stenosis height on the solute dispersion process is investigated. The results are validated with the previous solution without the effect of chemical reaction and stenosis. The results showed a good conformity between the two solutions. An increase in the chemical reaction coefficient, stenosis height, power-law index and plug flow radius reduces the dispersion function. It is observed that the solute dispersion in blood flow is affected by chemical reaction and stenosis height. H-B fluid is an appropriate fluid to investigate the blood velocity and transportation of the drug in blood flow to the targeted stenosed region through a very narrow artery for the treatment of arterial diseases. The results of the present study can potentially be used to predict the changes of blood flow behavior and dispersion process in blood flow.

Patient-specific hemodynamics modeling of carotid artery stenosis in a swine model based on 3D rotational angiography

Carotid stenosis is a common physiological abnormality that can cause a stroke or even death. For a clear understanding of its forming mechanism and potential damage, a hemodynamics model of carotid artery stenosis in a swine is built and analyzed based on surgery and ultrasonography. Eight Chinese mini-swine were partially ligated; transcranial Doppler and 3D DSA are employed to obtain physiological parameters for reconstructing the in vivo experimental vessel model. A numerical model of the swine blood flow and a detailed swine carotid vessel model with stenosis are proposed. The empirical function of WSS was validated for the swine model. Two models, a rigid wall and an elastic wall are precisely compared for pathological analysis of vascular diseases, such as carotid atherosclerosis and hemangioma. The elastic wall model performs better in representing experimental conditions while the rigid wall is much more efficient. Both models show that stenosis has a significant effect on resulting complex blood flow behavior and concentrated WSS distribution.

Effect of Thermal Radiation on Biomagnetic Fluid Flow and Heat Transfer over an Unsteady Stretching Sheet

This study examines the influence of thermal radiation on biomagnetic fluid, namely blood that passes through a two-dimensional stretching sheet in the presence of magnetic dipole. This analysis is conducted to observe the behavior of blood flow for an unsteady case, which will help in developing new solutions to treat diseases and disorders related to human body. Our model is namely biomagnetic fluid dynamics (BFD), which is consistent with two principles: ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD), where blood is treated as electrically conductive. It is assumed that the implemented magnetic field is sufficiently strong to saturate the ferrofluid, and the variation of magnetization with temperature may be approximated with the aid of a function of temperature distinction. The governing partial differential equations (PDEs) converted into ordinary differential equations (ODEs) using similarity transformation and numerical results are thus obtained by using the bvp4c function technique in MATLAB software with considering applicable boundary conditions. With the help of graphs, we discuss the impact of various parameters, namely radiation parameter, unsteady parameter, permeability parameter, suction parameter, magnetic field parameter, ferromagnetic parameter, Prandtl number, velocity and thermal slip parameter on fluid (blood) flow and heat transfer in the boundary layer. The rate of heat transfer and skin friction coefficient is also computationally obtained for the requirement of this study. The fluid velocity decreases with increasing values of the magnetic parameter, ferromagnetic interaction parameter, radiation parameter whereas temperature profile increases for the unsteady parameter, Prandtl number, and permeability parameter. From the analysis, it is also observed that the skin friction coefficient decreases and the rate of heat transfer increases respectively with increasing values of the ferromagnetic interaction parameter. The most important part of the present analysis is that we neither neglect the magnetization nor electrical conductivity of the blood throughout this study. To make the results more feasible, they are compared with the data previously published in the literature and found to be in good accuracy.

Mechanics of non-Newtonian blood flow in an artery having multiple stenosis and electroosmotic effects.

The electro-osmotically modulated hemodynamic across an artery with multiple stenosis is mathematically evaluated. The non-Newtonian behaviour of blood flow is tackled by utilizing Casson fluid model for this flow problem. The blood flow is confined in such arteries due to the presence of stenosis and this theoretical analysis provides the electro-osmotic effects for blood flow through such arteries. The mathematical equations that govern this flow problem are converted into their dimensionless form by using appropriate transformations and then exact mathematical computations are performed by utilizing Mathematica software. The range of the considered parameters is given as . The graphical results involve combine study of symmetric and non-symmetric structure for multiple stenosis. Joule heating effects are also incorporated in energy equation together with viscous effects. Streamlines are plotted for electro-kinetic parameter and flow rate . The trapping declines in size with incrementing , for symmetric shape of stenosis. But the size of trapping increases for the non-symmetric case.

Bioconvection Due to Gyrotactic Microorganisms in Couple Stress Hybrid Nanofluid Laminar Mixed Convection Incompressible Flow with Magnetic Nanoparticles and Chemical Reaction as Carrier for Targeted Drug Delivery through Porous Stretching Sheet.

In this paper, the steady electrically conducting hybrid nanofluid (CuO-Cu/blood) laminar-mixed convection incompressible flow at the stagnation-point with viscous and gyrotactic microorganisms is considered. Additionally, hybrid nanofluid flow over a horizontal porous stretching sheet along with an induced magnetic field and external magnetic field effects that can be used in biomedical fields, such as in drug delivery and the flow dynamics of the microcirculatory system. This investigation can also deliver a perfect view about the mass and heat transfer behavior of blood flow in a circulatory system and various hyperthermia treatments such as the treatment of cancer. The simple partial differential equations (PDEs) are converted into a series of dimensional ordinary differential equations (ODEs), which are determined using appropriate similarities variables (HAM). The influence of the suction or injection parameter, mixed convection, Prandtl number, buoyancy ratio parameter, permeability parameter, magnetic parameter, reciprocal magnetic prandtl number, bioconvection Rayleigh number, coupled stress parameter, thermophoretic parameter, Schmidt number, inertial parameter, heat source parameter, and Brownian motion parameter on the concentration, motile microorganisms, velocity, and temperature is outlined, and we study the physical importance of the present problem graphically.