OBJECTIVE Laminar shear stress is atheroprotective for endothelial cells (ECs), whereas nonlaminar, disturbed, or oscillatory shear stress correlates with development of atherosclerosis and neointimal hyperplasia. The effects of orbital and laminar shear stress on EC morphology, proliferation, and apoptosis were compared. METHODS ECs were exposed to orbital shear stress with an orbital shaker...

A variable coefficient Korteweg de Vries (VCKdV) system is derived by considering the timedependent basic flow and boundary conditions from a nonlinear, inviscid, nondissipative, and equivalent barotropic vorticity equation in a beta-plane. One analytical solution obtained from the VCKdV equation can be successfully used to explain the evolution of atmospheric dipoletype blocking (DB) life cycl...

Using a combination of theory, experiment, and simulation we investigate the nonlinear response of dense colloidal suspensions to large amplitude oscillatory shear flow. The time-dependent stress response is calculated using a recently developed schematic mode-coupling-type theory describing colloidal suspensions under externally applied flow. For finite strain amplitudes the theory generates a...

The dynamics of small spheres that are held by linear springs in a low Reynolds number shear flow at neighboring locations is investigated. The flow elongates the beads, and the interplay of the shear gradient with the nonlinear behavior of the hydrodynamic interaction among the spheres causes in a large range of parameters a bifurcation to a surprising oscillatory bead motion. The parameter ra...

A mesoscopic model of a diblock copolymer is used to study the stability of a lamellar structure under a uniform shear flow. We first obtain the nonlinear lamellar solutions under both steady and oscillatory shear flows. Regions of existence of these solutions are determined as a function of the parameters of the model and of the flow. Finally, we address the stability of the lamellar solution ...

Blood flow throughout the vascular circuit exerts a tangential force called shear stress upon all vessel walls. Under homeostatic conditions, shear stress is maintained within a narrow range. It has been shown that an alteration from this normal range of shear stress activates a biochemical signaling cascade in a process termed mechanotransduction. Although the signaling mechanism has not been ...

Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies have clarified the initiation mechanism of aneurysms, their growth mechanism remains unclear. Consequently, it is difficult to develop a diagnostic system for predicting aneurysm rup...

Large scale lattice Boltzmann simulations are utilized to investigate spinodal decomposition and structuring effects in binary immiscible and ternary amphiphilic fluid mixtures under shear. We use a highly scalable parallel Fortran 90 code for the implementation of the simulation method and demonstrate that adding surfactant to a system of immiscible fluid constituents can change the mixture’s ...

BACKGROUND Acute doses of elevated retrograde shear rate (SR) appear to be detrimental to endothelial function in resting humans. However, retrograde shear increases during moderate intensity exercise which also enhances post-exercise endothelial function. Since SR patterns differ with the modality of exercise, it is important to determine if augmented retrograde SR during exercise influences p...

1. The viscosity of sputum in patients with chronic bronchitis has been measured with the Weissenberg rheogoniometer, a cone and plate system, using oscillatory movement at low shear rates. 2. A characteristic pattern is described not previously reported for sputum or any other biological fluid. 3. Sputum viscosity decreased steadily with increasing shear rate; over a narrow range of shear rate...