We consider here pulsatile flow in circular tubes of varying cross-section with permeable walls. The fluid exchange across the wall is accounted for by prescribing the normal velocity of the fluid at the wall. A perturbation analysis has been carried out for low Reynolds number flows and for small amplitudes of oscillation. It has been observed that the magnitude of the wall shear stress and th...

Abstract The steady flow of Jeffrey fluid through a tube with both constrictions and dilatations have been studied. The expressions for velocity, pressure drop, volumetric flow rate, resistance to the flow, wall shear stress have been derived by assuming that the stenosis is mild. It is found that the resistance to the flow increases with the height of the stenosis and decreases with post steno...

Introduction: Microbubbles are widely used as contrast agent in diagnostic ultrasound. Recently they have shown good potential for applications in the therapeutic field such as drug delivery to the brain. Recent studies have shown focused ultrasound in conjunction with injected micro-bubbles could temporarily disrupt blood-brain barrier and let therapeutic agents transport into...

In this study, we characterized and modeled the rheology of TEMPO-oxidized cellulose nanofibril (NFC) aqueous suspensions with electrostatically stabilized and unflocculated nanofibrous structures. These colloidal suspensions of slender and wavy nanofibers exhibited a yield stress and a shear thinning behavior at low and high shear rates, respectively. Both the shear yield stress and the consis...

in this paper, turbulent mixed convective heat transfer of water and al2o3 nanofluid has been numerically studied in a horizontal tube under non-uniform heat flux on the upper wall and insulation in the lower wall using mixture model. for the discretization of governing equations, the second-order upstream difference scheme and finite volume method were used. the coupling of pressure and veloci...

BACKGROUND AND PURPOSE Little attention has been focused on the role of fluid-induced wall shear stress in fully developed cerebral aneurysms. The purpose of this study is to evaluate the alternation and distribution of wall shear stress over 1 cardiac cycle in patients' aneurysms. METHODS A middle cerebral artery aneurysm and a basilar tip aneurysm with localized outpouching (blebs) in their...

We report measurements of the static shear modulus of electrorheological (ER) fluids consisting of water-wetted silica microspheres in silicone oil. A shear-annealing method, using creep-recovery (CR) cycles under an external electric field, is used to enhance ER properties of the fluid. The shear-annealing method enables the silica spheres in the ER fluid to form better aligned and denser colu...

Alterations in the functions of vascular endothelial cells (ECs) induced by fluid shear stress may play a pivotal role in both the development and prevention of vascular diseases. We found that DNA synthesis of bovine aortic and human umbilical vein ECs, determined by [H]thymidine incorporation, was inhibited by steady laminar shear stress (5 and 30 dyne/cm). This growth inhibition due to shear...

Blood vessels alter their morphology and function in response to changes in blood flow, and their responses are based on blood flow detection by the vascular endothelium. Endothelial cells (ECs) covering the inner surface of blood vessels sense shear stress generated by flowing blood and transmit the signal into the interior of the cell, which evokes a cellular response. The EC response to shea...