scholarly journals Comparison of Newtonian and Non-newtonian Fluid Models in Blood Flow Simulation in Patients With Intracranial Arterial Stenosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Haipeng Liu ◽  
Linfang Lan ◽  
Jill Abrigo ◽  
Hing Lung Ip ◽  
Yannie Soo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Newtonian Fluid ◽  
Fluid Model ◽  
Arterial Stenosis ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Fluid Models ◽  
Cfd Models ◽  
Atherosclerotic Stenosis ◽  
Transient Simulations

BackgroundNewtonian fluid model has been commonly applied in simulating cerebral blood flow in intracranial atherosclerotic stenosis (ICAS) cases using computational fluid dynamics (CFD) modeling, while blood is a shear-thinning non-Newtonian fluid. We aimed to investigate the differences of cerebral hemodynamic metrics quantified in CFD models built with Newtonian and non-Newtonian fluid assumptions, in patients with ICAS.MethodsWe built a virtual artery model with an eccentric 75% stenosis and performed static CFD simulation. We also constructed CFD models in three patients with ICAS of different severities in the luminal stenosis. We performed static simulations on these models with Newtonian and two non-Newtonian (Casson and Carreau-Yasuda) fluid models. We also performed transient simulations on another patient-specific model. We measured translesional pressure ratio (PR) and wall shear stress (WSS) values in all CFD models, to reflect the changes in pressure and WSS across a stenotic lesion. In all the simulations, we compared the PR and WSS values in CFD models derived with Newtonian, Casson, and Carreau-Yasuda fluid assumptions.ResultsIn all the static and transient simulations, the Newtonian/non-Newtonian difference on PR value was negligible. As to WSS, in static models (virtual and patient-specific), the rheological difference was not obvious in areas with high WSS, but observable in low WSS areas. In the transient model, the rheological difference of WSS areas with low WSS was enhanced, especially during diastolic period.ConclusionNewtonian fluid model could be applicable for PR calculation, but caution needs to be taken when using the Newtonian assumption in simulating WSS especially in severe ICAS cases.

scholarly journals Analysis of Blood Flow in Arterial Stenosis Using Casson and Power-Law Fluid Model

2013 ◽  
Vol 14 (2) ◽  
pp. 73
Author(s):  
Riri Jonuarti
Keyword(s):  
Blood Flow ◽  
Power Law ◽  
Fluid Model ◽  
Blood Flow Rate ◽  
Casson Fluid ◽  
Arterial Stenosis ◽  
Fluid Models ◽  
Power Law Fluid ◽  
Pass Through ◽  
Flow Power

Simulation of blood flow behaviour in the arteries and in arterial stenosis has been made and will be discussed in this paper. This simulation uses pulsatile flow and blood flow in artery without stenosis is considered as a dynamic fluid, compressed and condensed. Whereas, in the case of arterial stenosis has been used Casson and Power-law fluid models. In the arteries without stenosis, blood flow velocity profiles show the same pattern for each Womersley number, but with different speed value. In the case of arterial stenosis, blood flow rate decreases with increasing stenosis position away from axis of blood vessels. Resistances to flow are increases with increasing the size (height and length) of stenosis, both for the Casson and Power-law fluid models. If resistance to flow increases, it is more difficult for the blood to pass through an artery, result the flow decreases and heart has to work harder to maintain adequate circulation.Keywords : Artery, blood flow, power-law fluid, Casson fluid, stenosis  

Numerical simulation of blood nanofluid flow over three different geometries by means of gyrotactic microorganisms: Applications to the flow in a circulatory system

2020 ◽  
pp. 095440622094745 ◽  
Author(s):  
H Thameem Basha ◽  
R Sivaraj
Keyword(s):  
Blood Flow ◽  
Stagnation Point ◽  
Newtonian Fluid ◽  
Fluid Transport ◽  
Fluid Model ◽  
Circulatory System ◽  
Blood Flow Rate ◽  
Fluid Models ◽  
Gyrotactic Microorganisms ◽  
Tangent Hyperbolic Fluid

Biomedical engineers, medical scientists, and clinicians are expressing a notable interest in the measurement of blood flow rate because it is used to detect cardiovascular diseases such as atherosclerosis and arrhythmia. Several researchers have adopted various non-Newtonian fluid models to investigate blood flow in the circulatory system. Because many non-Newtonian fluid models like Herschel Buckley, Powell-Eyring fluid, tangent hyperbolic fluid, and Williamson fluid exhibit the characteristics of blood. The tangent hyperbolic fluid model expresses the rheological characteristics of blood more accurately due to its shear-thinner properties. This work is performed to express the significance of the induced magnetic field and gyrotactic microorganisms on the flow of tangent hyperbolic nanofluid over a plate, wedge and stagnation point of the plate. Suitable self-similarity variables are employed to convert the fluid transport equations into ordinary differential equations which have been solved with the use of the Runge-Kutta-Fehlberg (RKF) approach. The impacts of active parameters on transport properties of the fluid are illustrated with graphs and tables. The growing magnetic parameter lessens the blood nanofluid velocity over three geometries. Blood nanofluid has a higher heat transfer rate over a stagnation point compared with other two geometries. Blood nanofluid temperature augments for uplifting the thermophoresis parameter. Peclet number shows a high impact on microorganisms density in a blood nanofluid. This exploration can provide a clear view regarding the heat and mass transfer behavior of blood flow in a circulatory system and various hyperthermia treatments like treatment of cancer.

Abstract 566: Experimental Investigation of Blood Flow in the Femoral Bifurcated Artery

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Azadeh Lotfi ◽  
Zachary Lawler ◽  
Omar Jan ◽  
Tracie Barber ◽  
Anne Simmons
Keyword(s):  
Blood Flow ◽  
Additional Treatment ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Local Flow ◽  
Micro Piv ◽  
Stent Restenosis ◽  
Tibial Arteries ◽  
Hemodynamic Disturbance ◽  
Good Patency

Stent implantation is one of the most widely used interventional treatments for arterial stenosis which occurs predominantly due to atherosclerosis. Although stent placement can ensure very good patency of the lumen, stent-induced hemodynamic disturbance, which can lead to further stenosis, still remains a common clinical complication. This study investigates the degree of hemodynamic disturbance induced by stenting an idealized bifurcated popliteal artery, which branches into the anterior and posterior tibial arteries, and is known as a site prone to atherosclerosis. Both stent-free and stented bifurcated arteries were examined, and the local flow patterns analysed for the comparative disturbance through the use of Micro Particle Image Velocity (micro-PIV) system. A life-size model of the artery was reconstructed using dimensions obtained from a patient specific MRI scan. The experiments were conducted under steady flow conditions, and the flow rates across the bifurcation were visualized and measured using the micro-PIV system. It was shown that hemodynamic disturbances induced by the blood flow over the stent can further disrupt the arterial wall downstream of the stent causing further downstream vascular damage in addition to the in-stent restenosis. This downstream vascular disruption may require additional treatment depending on the type and severity of the damage. The results also support the hypothesis that links certain flow dynamic behaviour with the development of early intimal thickening, as the near wall low fluid momentum regions are found at locations where thickening was localized in bifurcated arteries in clinical studies.

NEWTONIAN AND NON-NEWTONIAN BLOOD FLOW AT A 90∘-BIFURCATION OF THE CEREBRAL ARTERY: A COMPARATIVE STUDY OF FLUID VISCOSITY MODELS

2018 ◽  
Vol 18 (05) ◽  
pp. 1850043 ◽  
Author(s):  
S. V. FROLOV ◽  
S. V. SINDEEV ◽  
D. LIEPSCH ◽  
A. BALASSO ◽  
P. ARNOLD ◽  
...  
Keyword(s):  
Blood Flow ◽  
Newtonian Fluid ◽  
Flow Rate ◽  
Fluid Model ◽  
Cerebral Arteries ◽  
High Viscosity ◽  
Flow Rate Ratio ◽  
Parent Artery ◽  
Fluid Viscosity ◽  
Recirculating Flow

The majority of numerical simulations assumes blood as a Newtonian fluid due to an underestimation of the effect of non-Newtonian blood behavior on hemodynamics in the cerebral arteries. In the present study, we evaluated the effect of non-Newtonian blood properties on hemodynamics in the idealized 90[Formula: see text]-bifurcation model, using Newtonian and non-Newtonian fluids and different flow rate ratios between the parent artery and its branch. The proposed Local viscosity model was employed for high-precision representation of blood viscosity changes. The highest velocity differences were observed at zones with slow recirculating flow. During the systolic peak the average difference was 17–22%, whereas at the end of diastole the difference increased to 27–60% depending on the flow rate ratio. The main changes in the viscosity distribution were observed distal to the flow separation point, where the non-Newtonian fluid model produced 2.5 times higher viscosity. A presence of such high viscosity region substantially affected the size of the flow recirculation zone. The observed differences showed that non-Newtonian blood behavior had a significant effect on hemodynamic parameters and should be considered in the future studies of blood flow in cerebral arteries.

Computational Modeling of Shear-Based Hemolysis Caused by Renal Obstruction

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Polina A. Segalova ◽  
K. T. Venkateswara Rao ◽  
Christopher K. Zarins ◽  
Charles A. Taylor
Keyword(s):  
Blood Flow ◽  
Boundary Conditions ◽  
Renal Artery ◽  
Aortic Aneurysms ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Shear Stresses ◽  
Baseline Model ◽  
Implantable Medical Devices ◽  
Renal Obstruction

As endovascular treatment of abdominal aortic aneurysms (AAAs) gains popularity, it is becoming possible to treat certain challenging aneurysmal anatomies with endografts relying on suprarenal fixation. In such anatomies, the bare struts of the device may be placed across the renal artery ostia, causing partial obstruction to renal artery blood flow. Computational fluid dynamics (CFD) was used to simulate blood flow from the aorta to the renal arteries, utilizing patient-specific boundary conditions, in three patient models and calculate the degree of shear-based blood damage (hemolysis). We used contrast-enhanced computed tomography angiography (CTA) data from three AAA patients who were treated with a novel endograft to build patient-specific models. For each of the three patients, we constructed a baseline model and endoframe model. The baseline model was a direct representation of the patient’s 30-day post-operative CTA data. This model was then altered to create the endoframe model, which included a ring of metallic struts across the renal artery ostia. CFD was used to simulate blood flow, utilizing patient-specific boundary conditions. Pressures, flows, shear stresses, and the normalized index of hemolysis (NIH) were quantified for all patients. The overall differences between the baseline and endoframe models for all three patients were minimal, as measured though pressure, volumetric flow, velocity, and shear stress. The average NIH across the three baseline and endoframe models was 0.002 and 0.004, respectively. Results of CFD modeling show that the overall disturbance to flow caused by the presence of the endoframe struts is minimal. The magnitude of the NIH in all models was well below the accepted design and safety threshold for implantable medical devices that interact with blood flow.

A Hemodynamic Comparison of Myocardial Bridging and Coronary Atherosclerotic Stenosis: A Computational Model with Experimental Evaluation

2020 ◽  
Author(s):  
Mohammadali Sharzehee ◽  
Yasamin Seddighi ◽  
Eugene A. Sprague ◽  
Ender A. Finol ◽  
Hai-Chao Han
Keyword(s):  
Pressure Drop ◽  
Experimental Results ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Flow Loop ◽  
Myocardial Bridging ◽  
Atherosclerotic Stenosis ◽  
Stenosis Severity ◽  
The Difference

Abstract Myocardial bridging (MB) and coronary atherosclerotic stenosis can impair coronary blood flow and may cause myocardial ischemia or even stoke. It remains unclear how MB and stenosis are similar or different regarding their impacts on coronary hemodynamics. The purpose of this study was to compare the hemodynamic effects of MB and stenosis using experimental and computational fluid dynamics (CFD) approaches. For CFD modeling, three MB patients with different levels of lumen obstruction such as mild, moderate, and severe were selected. Patient-specific left anterior descending coronary artery models were reconstructed from biplane angiograms. For each MB patient, the virtually healthy and stenotic models were also simulated for comparison. In addition, an in vitro flow-loop was developed to evaluate the model-predicted pressure drop. The CFD modeling results demonstrated that the difference between MB and stenosis increased with increasing MB/stenosis severity and flow rate. Experimental results showed that increasing the MB length (by 140%) only had significant impact on the pressure drop in the severe MB (39% increase at the exercise). However, increasing the stenosis length dramatically increased the pressure drop in both moderate and severe stenoses at all flow rates (31% and 93% increase at the exercise, respectively). Both CFD and experimental results confirmed that the MB had a higher maximum and a lower mean pressure drop in comparison with the stenosis, regardless of MB/stenosis severity. A better understanding of MB and stenosis may improve the therapeutic strategies in coronary disease patients and prevent acute coronary syndromes.

scholarly journals UNSTEADY TWO-LAYERED BLOOD FLOW THROUGH A -SHAPED STENOSED ARTERY USING THE GENERALIZED OLDROYD-B FLUID MODEL

2016 ◽  
Vol 58 (1) ◽  
pp. 96-118 ◽  
Author(s):  
AKBAR ZAMAN ◽  
NASIR ALI ◽  
O. ANWAR BEG ◽  
M. SAJID
Keyword(s):  
Blood Flow ◽  
Differential Equations ◽  
Newtonian Fluid ◽  
Numerical Solutions ◽  
Fluid Model ◽  
Initial Boundary ◽  
Momentum Conservation ◽  
Rheological Parameters ◽  
Stenosed Artery ◽  
Flow Through

A theoretical study of an unsteady two-layered blood flow through a stenosed artery is presented in this article. The geometry of a rigid stenosed artery is assumed to be$w$-shaped. The flow regime is assumed to be laminar, unsteady and uni-directional. The characteristics of blood are modelled by the generalized Oldroyd-B non-Newtonian fluid model in the core region and a Newtonian fluid model in the periphery region. The governing partial differential equations are derived for each region by using mass and momentum conservation equations. In order to facilitate numerical solutions, the derived differential equations are nondimensionalized. A well-tested explicit finite-difference method (FDM) which is forward in time and central in space is employed for the solution of a nonlinear initial boundary value problem corresponding to each region. Validation of the FDM computations is achieved with a variational finite element method algorithm. The influences of the emerging geometric and rheological parameters on axial velocity, resistance impedance and wall shear stress are displayed graphically. The instantaneous patterns of streamlines are also presented to illustrate the global behaviour of the blood flow. The simulations are relevant to haemodynamics of small blood vessels and capillary transport, wherein rheological effects are dominant.

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