The viscometric functions for shear flow as predicted by the inextensible reptating rope model have been analysed numerically and analytically. The results obtained are compared with the predictions of the Curtiss-Bird theory. It is shown that if the correlation length of the rope is small as compared to its contour length significant deviations from the Curtiss-Bird theory are obtained. Result...

The paper presents experimental evidence for the potentials of CFD methodology in revealing external flow and inner flow shear deformation rates in stirred tanks. Two basic issues are considered: could CFD produce valid solutions for shear rates in mixing vessels, and could practical shear rate differences relevant to specific impeller designs be reproduced by CFD. In a first part, the shear ra...

We perform extensive molecular dynamics simulations of two-dimensional frictionless granular materials to determine whether these systems can be characterized by a single static yield shear stress. We consider boundary-driven planar shear at constant volume and either constant shear force or constant shear velocity. Under steady flow conditions, these two ensembles give similar results for the ...

PURPOSE Restenosis due to distal anastomotic intimal hyperplasia, a leading cause of arterial bypass graft failure, is thought to be promoted by hemodynamic effects, specifically 'abnormal' wall shear stress patterns. The purpose of this study was to quantify the effects of flow waveform on peri-anastomotic flow and wall shear stress patterns. METHODS Blood flow and wall shear stress patterns...

The rheology of solvent-filled polymer brushes under steady and oscillatory shear is studied by Brownian dynamics simulation. The flow field is solved self-consistently with the polymer dynamics. We find that under steady flow the brushes are shear thinning in both normal forces and shear viscosity. During oscillatory flow, extreme shear thickening occurs when the ratio of the Weissenberg numbe...

BACKGROUND Physical forces, such as pressure and flow, are well known to affect vascular function in the coronary circulation. Increases in shear stress produce vasodilation in coronary arterioles in vitro, and constant-flow preparations suggest a role for shear stress-induced vasodilation during adjustments to metabolic demand in vivo. Hypothetically, the regulation of shear stress can be view...

Ceramic powder (zirconia) was mixed with binder consisting polypropylene, paraffin and stearic acid in elastic extruder. Steady and oscillatory shear flow properties of these materials in the molten state were measured on a cone-plate rheometer; parallel superposed steady and oscillatory shear flow experiments were also carried out. Moreover, flow properties at high shear rates were measured on...

background: the interaction between the blood and the vessel wall is of great clinical interest in studying cardiovascular diseases, the major causes of death in developed countries. objective: to understand the effects of incorporating fluid-structure interaction into the simulation of blood flow through an anatomically realistic model of abdominal aorta and renal arteries reconstructed from c...

the efficiency of a collar in reducing the scour depth around circular and rectangular piers is studied at different flow intensities (ratio of upstream shear stress to sediment critical shear stress). rectangular piers aligned with the flow as well as skewed at 5º, 10º, 20º were examined. previous studies had shown that with collar the equilibrium time of scouring increases considerably. to re...

The wall shear stress pattern was measured in a rigid plastic cast of a canine artery during steady flow by means of an electrochemical technique. The topographic distribution of shear stress is very nonuniform, with regions of high and low shear in close proximity. The steady shear stresses are highest at the leading edge of flow dividers and at the entrance regions to branch vessels. The shap...