This paper describes the conditions for initiation and maintenance of secondary currents in open channel flows. By analyzing the Reynolds equation in the wall-normal and wall-tangent directions, this study reveals that, like other types of vortices, the secondary currents are originated in the near-boundary region, and the magnitude (or strength) of secondary flow is proportional to the lateral...

The fluctuating bed shear stress has largely been investigated only for the conditions of uniform channel flows and boundary layers. In practical engineering, the flow conditions are often modified due to the presence of various hydraulic structures. To what extent the modification affects the known characteristics of the bed shear stress is not clear. This study presents experimental results o...

With the assumption that the bed shear stress fluctuates in a lognormal fashion, the probability density function (pdf) of the standardised bed shear stress is derived as a function of the relative shear stress intensity. The pdf is more skewed with larger relative intensities, but approaches a Gaussian function when the relative intensity is small. The computed pdf agrees well with the reporte...

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...

We consider a variant of the classical ‘Rayleigh problem’ (‘Stokes’s first problem’) in which a semi-infinite region of initially quiescent fluid is mobilised by a shear stress applied suddenly to its boundary. We show that self-similar solutions for the fluid velocity are available for any generalised Newtonian fluid, regardless of its constitutive law. We demonstrate how these solutions may b...

A three-dimensional computer model of human aortic arch with three branches is reproduced to study the pulsatile blood flow with Finite Element Method. In specific, the focus is on variation of wall shear stress, which plays an important role in the localization and development of atherosclerotic plaques. Pulsatile pressure pulse is used as boundary condition to avoid flow entry development, an...

We used computer simulations to study spontaneous strain localization in granular materials, as a result of symmetry breaking non-homogeneous deformations. Axisymmetric triaxial shear tests were simulated by means of standard three-dimensional Distinct Element Method (DEM) with spherical grains. Carefully prepared dense specimens were compressed between two platens and, in order to mimic the ex...

The shear strength of reinforced concrete members without shear reinforcement is related to the shear stress carried by the concrete effective shear area. For rectangular sections the effective shear area represents the area corresponding to the effective depth. However, for circular sections this area is not as readily defined. Different empirical proposals have been suggested recently but no ...

In this paper, a displacement-based, variationally consistent, two variable refined theory for shear deformable beams is presented. The beam is assumed to be of linearly elastic, homogeneous, isotropic material and has a uniform rectangular cross-section. In this theory, the beam axial displacement and beam transverse displacement consist of bending components and shearing components. The assum...

BACKGROUND AND PURPOSE A recent randomized clinical trial on intracranial atherosclerosis was discontinued because of the higher frequency of stroke and death in the angioplasty and stent placement group than in the medical treatment group. An in-depth understanding of the relationship between biologic responses and flow dynamics is still required to identify the current limitations of intracra...