In this work we propose a novel approach to model order reduction for incompressible fluid flows that focuses on the spatio-temporal description of the stresses on the surface of a body, i.e. of the wall shear stress and of the wall pressure. The spatial representation of these two variables is given by a compact set of “wall basis functions”, i.e. elementary basis functions defined on the wall...

PURPOSE The aim of this study was to investigate the blood flow in the end-to-side arteriovenous (a-v) fistula, taking into account its pulsating nature and the patient-specific geometry of blood vessels. Computational Fluid Dynamics (CFD) methods were used for this analysis. METHODS DICOM images of the fistula, obtained from the angio-computed tomography, were a source of the data applied to...

Coupled fluid–structure interaction (FSI) analysis of the human right coronary artery (RCA) has been carried out to investigate the effects of wall compliance on coronary hemodynamics. A 3-D model of a stenosed RCA was reconstructed based on multislice computerized tomography images. A velocity waveform in the proximal RCA and a pressure waveform in the distal RCA of a patient with a severe ste...

BACKGROUND Maintaining flow in a newly established high-flow bypass into the intracranial circulation may be threatened by low blood pressure. OBJECTIVE To identify mean arterial blood pressure below which early graft failure may ensue. METHODS Computational fluid dynamic blood flow simulation and Doppler ultrasound-derived velocities were combined to study 12 patients with common carotid-t...

The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinc...

A novel near-wall modeling for large-eddy simulation based on the lattice Boltzmann method is proposed. An existing reconstruction of distribution functions further developed to calculate high Reynolds number wall-bounded turbulent flow a non-body-fitted Cartesian grid. The following three ideas are introduced into model: (1) introduction an image-point, (2) blending sub-grid scale and Reynolds...

PURPOSE To evaluate wall shear stress (WSS) on retinal microcirculation noninvasively. METHODS Retinal vessel diameter (D) and mean centerline blood velocity (V(max, mean)) were measured in the retinal arterioles and venules at first- and second-order branches in 13 subjects using laser Doppler velocimetry (LDV). Retinal blood flow (RBF) and wall shear rate (WSR) were calculated using these t...

The steel shear wall and composite steel plate shear wall is introduced in recent three decade and is considered and is spread rapidly. Composite steel plate shear wall which is made of a layer of thin steel sheet with coating of reinforced concrete in one or both sides of steel palate is considered a third generation of resistance shear walls against lateral loads that in addition to increasin...

The predilection of atherosclerotic lesions for specific sites in the arterial tree is believed to be related t o the wall shear stress, exerted by the blood flow. Measurement of the magnitude of the wall shear stress is difficult and is frequently determined by an extrapolation of the velocity field t o find the wall shear rate and an estimation of the viscosity of the fluid in the neighborhoo...

BACKGROUND An autogenous arteriovenous fistula is the optimal vascular access for hemodialysis. In the case of brachiocephalic fistula, cephalic arch stenosis commonly develops leading to access failure. We have hypothesized that a contribution to fistula failure is low wall shear stress resulting from post-fistula creation hemodynamic changes that occur in the cephalic arch. METHODS Twenty-t...