Elongation of the proximal descending thoracic aorta and associated hemodynamics increase the risk of acute type B aortic dissection.

Background: Acute type B aortic dissection (ATBAD) is a life-threatening aortic disease. However, little information is available on predicting and understanding of ATBAD.

Objective: The study sought to explore the underlying mechanism of ATBAD by analyzing the morphological and hemodynamic characteristics related to aortic length.

Hemodynamics of different configurations of the left subclavian artery parallel stent graft for thoracic endovascular aortic repair.

Background And Objective: Parallel (chimney and periscope) graft technique is an effective approach for left subclavian artery (LSA) reconstruction in patients treated by thoracic endovascular aortic repair (TEVAR) for the inadequate landing zone. However, certain stent graft (SG) configurations may promote thrombosis and reduce distal blood flow, increasing risks of cerebral infarction and reintervention.

Methods: In this paper, we first attempt to systematically evaluate the hemodynamic performances of different parallel graft techniques as potential determinants of complication risks.

Enlarged Lumen Volume of Proximal Aortic Segment and Acute Type B Aortic Dissection: A Computer Fluid Dynamics Study of Ideal Aortic Models.

Background: Recent study has revealed that enlarged diameters of the ascending aorta and proximal aortic arch enhance the probability of ATBAD. However, little is understood about the relation to ATBAD.

Objective: This study explored the differences in proximal aortic segment (PAS) morphology in patients with acute type B aortic dissection (ATBAD), and performed hemodynamic simulations to provide proof of principle.

Quantitative analysis of renal blood flow during thoracic endovascular aortic repair in type B aortic dissection using iFlow.

Background: Currently, the thoracic endovascular aortic repair is the recommended clinical treatment for type B aortic dissections. Unfortunately, malperfusion or ischemia of the kidneys is a major complication of type B aortic dissections. Despite this, few studies have focused on the effects of thoracic endovascular aortic repair on blood flow in renal arteries and parenchyma.

Numerical investigations of temperature and hemodynamics in carotid arteries with and without atherosclerotic plaque during open surgery.

Intraoperative monitoring is essential for providing safe and effective care during open surgery. In this paper, numerical simulation is performed to track the flow and heat transfer of carotid arteries with and without atherosclerotic plaque in a real physiological system during surgery, in which the heat transport is first considered to couple to the blood flow due to the temperature dependence of the blood viscosity. The impacts of the operating room temperature and hematocrit (H) on the viscosity, velocity, temperature, wall shear stress (WSS), pressure drop and oscillation are investigated.

Numerical simulation of magnetic nano drug targeting to atherosclerosis: Effect of plaque morphology (stenosis degree and shoulder length).

Background And Objective: Nanoparticle-mediated targeted drug delivery is a promising option for treatment of atherosclerosis. However, the drug targeting may be affected by multiple factors. Considerable attentions have been focused on the influences of external factors, e.

Analysis of the formation mechanism and occurrence possibility of Post-Stenotic Dilatation of the aorta by CFD approach.

Background And Objective: Post-Stenotic Dilatation (PSD), the common complication of coarctation of the aorta (COA), is a progressive disease involving aortic aneurysm and even rupture. However, there has been no definitive method that could investigate the mechanism of PSD formation, progression and rupture. The purpose of the present work is to analyze the mechanism behind PSD formation and to further assess the risk of COA patients with different coarctation degrees deteriorating into PSD.

A novel investigation of a micropolar fluid characterized by nonlinear constitutive diffusion model in boundary layer flow and heat transfer.

The rheological and heat-conduction constitutive models of micropolar fluids (MFs), which are important non-Newtonian fluids, have been, until now, characterized by simple linear expressions, and as a consequence, the non-Newtonian performance of such fluids could not be effectively captured. Here, we establish the novel nonlinear constitutive models of a micropolar fluid and apply them to boundary layer flow and heat transfer problems. The nonlinear power law function of angular velocity is represented in the new models by employing generalized "-diffusion theory," which has successfully described the characteristics of non-Newtonian fluids, such as shear-thinning and shear-thickening fluids.

Fractal aggregation kinetics contributions to thermal conductivity of nano-suspensions in unsteady thermal convection.

Nano-suspensions (NS) exhibit unusual thermophysical behaviors once interparticle aggregations and the shear flows are imposed, which occur ubiquitously in applications but remain poorly understood, because existing theories have not paid these attentions but focused mainly on stationary NS. Here we report the critical role of time-dependent fractal aggregation in the unsteady thermal convection of NS systematically. Interestingly, a time ratio λ = t/t (t is the aggregate characteristic time, t the mean convection time) is introduced to characterize the slow and fast aggregations, which affect distinctly the thermal convection process over time.

A Novel Equivalent Agglomeration Model for Heat Conduction Enhancement in Nanofluids.

We propose a multilevel equivalent agglomeration (MEA) model in which all particles in an irregular cluster are treated as a new particle with equivalent volume, the liquid molecules wrapping the cluster and in the gaps are considered to assemble on the surface of new particle as mixing nanolayer (MNL), the thermal conductivity in MNL is assumed to satisfy exponential distribution. Theoretical predictions for thermal conductivity enhancement are highly in agreement with the classical experimental data. Also, we first try to employ TEM information quantitatively to offer probable reference agglomeration ratio (not necessary a very precise value) to just test rational estimations range by present model.

The exterior unsteady viscous flow and heat transfer due to a porous expanding or contracting cylinder.

Since the vessels in the biological tissues are characterized by low seepage Reynolds numbers and contracting or expanding walls, more attention is paid on the viscous flow outside the porous pipe with small expansion or contraction. This paper presents a numerical solution of the flow and heat transfer outside an expanding or contracting porous cylinder. The coupled nonlinear similarity equations are solved by Bvp4c, which is a collocation method with MATLAB.

Asymmetric viscoelastic flow through a porous channel with expanding or contracting walls: a model for transport of biological fluids through vessels.

In this article, the asymmetric viscoelastic fluid in a rectangular domain bounded by two porous moving channels with expanding or contracting walls is investigated. The governing equations are reduced to an ordinary equation by using suitable similar transformations. Homotopy analysis method is used to obtain the expression for velocity fields.

The effects of slip velocity on a micropolar fluid through a porous channel with expanding or contracting walls.

In this paper, a simple mathematical model depicting blood flow in the deforming porous channel is developed with an emphasis on the permeability property of the blood vessel and slip boundary based on Beavers and Joseph slip condition. In this study, the blood is represented by a micropolar fluid. With such an ideal model, the governing equations are reduced to ordinary ones by introducing suitable similar transformations.