Topic
Depth–slope product
About: Depth–slope product is a research topic. Over the lifetime, 2 publications have been published within this topic receiving 10 citations.
Papers
31 Jan 2011
TL;DR: In this paper, a novel shear plate was used to measure the forces on a fixed bed under a range of irregular wave trains, and the results indicated that an offshore bed shear stress may be recorded while the free stream velocity remains onshore at all times.
Abstract: Standard engineering methods of estimating bed shear stress using friction factors ctors (ie Tb 2 = 1/2 f u2) can fail spectacularly in unsteady hydrodynamic conditions This paper demonstrates this fact using direct measurements of bed shear stresses under irregular waves The measurement of the bed shear stress in unsteady hydrodynamic conditions is a challenging task It is often done in an indirect manner by measuring the velocity profile and inferring the associated laminar or turbulent shear stresses However this technique is limited in application, particularly if the relative roughness is large, and therefore direct measurement of the shear stress is preferable, and useful as a validation of other techniques A novel shear plate apparatus was used to measure the forces on a fixed bed under a range of irregular wave trains The measurements are explained in terms of the influence of the horizontal pressure gradient and the shear stresses acting on the surface of the plate The horizontal fluid velocity at the edge of the boundary layer and the water surface elevation and slope were also measured The paper demonstrates that the water surface measurements can be used to obtain accurate estimates of the forces on the bed, by employing Fourier analysis techniques or an innovative convolution integral method The experimental results indicate that an offshore bed shear stress may be recorded while the free stream velocity remains onshore at all times This demonstrates the failure of the standard engineering friction factor method in this scenario, since negative friction factors would be required To date there have been very few studies reporting time series of bed shear stress in unsteady flow conditions Hence this data set provides an opportunity to investigate the phasing and magnitude of the forces on the bed that drive sediment transport processes Important questions are also raised regarding the appropriate definition for the bed shear stress when the vertical gradient of the shear stress is large
9 citations
Journal Article•
TL;DR: In this article, the authors compared the bed shear stress in uniform and non-uniform flows in open channels under different hydraulic conditions, and concluded that the formulas for the mean and the mean bed-shear stress distribution were applicable in uniform flow, but not all of the formulas are applicable in nonuniform flow.
Abstract: Based on experimental data measured with a Preston tube,bed shear stresses in uniform and non-uniform flows in open channels were compared under different hydraulic conditions.It is concluded that the formulas for bed shear stress along the center-line,the mean bed shear stress and the bed shear stress distribution are applicable in uniform flow,but not all of the formulas are applicable in non-uniform flow.For uniform flow,the shear stress increases with the discharge at the same slope,and it increases with the slope at the same discharge,while the bed shear stresses in non-uniform flow are almost the same at the same relative water depth.
1 citations
Performance Metrics
| Year | Papers |
|---|---|
| 2011 | 1 |
| 2007 | 1 |