A Floating-Element Drag Plate for Direct Measurement of Bed Shear Stress During Eolian Transport

An omnidirectional wall shear meter has been developed which is capable of the direct measurement of both magnitude and direction of wall shear stress. Linearity, resolution, and accuracy have been demonstrated analytically and experimentally by static and dynamic calibration. The floating element device works on the cantilevered beam principle. Eddy current probes, set at right angles to the beam and to each other, sense the magnitude and direction of deflection which can be calibrated against known force loadings. The device is used to measure wall shear stress in three-dimensional flows, and was specifically developed as a means of validating proposed three-dimensional near-wall similarity laws.

Download Full-text

Efficiency prediction for storage chambers using computational fluid dynamics

Water Science & Technology ◽

10.2166/wst.1996.0202 ◽

1996 ◽

Vol 33 (9) ◽

pp. 163-170 ◽

Cited By ~ 4

Author(s):

Virginia R. Stovin ◽

Adrian J. Saul

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Shear Stress ◽

Particle Tracking ◽

Critical Value ◽

Complex Geometries ◽

Bed Shear Stress ◽

Breadth Ratio ◽

Computational Fluid Dynamics Cfd ◽

Simulated Flow

Research was undertaken in order to identify possible methodologies for the prediction of sedimentation in storage chambers based on computational fluid dynamics (CFD). The Fluent CFD software was used to establish a numerical model of the flow field, on which further analysis was undertaken. Sedimentation was estimated from the simulated flow fields by two different methods. The first approach used the simulation to predict the bed shear stress distribution, with deposition being assumed for areas where the bed shear stress fell below a critical value (τcd). The value of τcd had previously been determined in the laboratory. Efficiency was then calculated as a function of the proportion of the chamber bed for which deposition had been predicted. The second method used the particle tracking facility in Fluent and efficiency was calculated from the proportion of particles that remained within the chamber. The results from the two techniques for efficiency are compared to data collected in a laboratory chamber. Three further simulations were then undertaken in order to investigate the influence of length to breadth ratio on chamber performance. The methodology presented here could be applied to complex geometries and full scale installations.

Download Full-text

Particle Responses to Near-Bed Shear Stress in a Shallow, Wave- and Current-Driven Environment

10.1002/essoar.10507100.1 ◽

2021 ◽

Author(s):

Grace Chang ◽

Galen Egan ◽

Joseph D McNeil ◽

Samuel McWilliams ◽

Craig Jones ◽

...

Keyword(s):

Shear Stress ◽

Bed Shear Stress

Download Full-text

Study on bed shear stress around channel constriction.

Doboku Gakkai Ronbunshu ◽

10.2208/jscej.1985.357_115 ◽

1985 ◽

pp. 115-121

Author(s):

Susumu HASHIMOTO ◽

Yoshitaka FUKUI ◽

Hideo KIKKAWA

Keyword(s):

Shear Stress ◽

Bed Shear Stress ◽

Channel Constriction

Download Full-text

The influence of deposit body on the near-bed shear stress

Proceedings of the Institution of Civil Engineers - Water Management ◽

10.1680/jwama.20.00139 ◽

2021 ◽

pp. 1-29

Author(s):

Yan He ◽

Jing Zhang ◽

Huling Jiang ◽

Zhixue Guo ◽

Hongxi Zhao

Keyword(s):

Shear Stress ◽

Bed Shear Stress

Download Full-text

Roughness Element Geometry Required for Wind Tunnel Simulations of the Atmospheric Wind

Journal of Fluids Engineering ◽

10.1115/1.3448821 ◽

1977 ◽

Vol 99 (3) ◽

pp. 480-485 ◽

Cited By ~ 16

Author(s):

I. S. Gartshore ◽

K. A. De Croos

Keyword(s):

Boundary Layer ◽

Shear Stress ◽

Wind Tunnel ◽

Roughness Element ◽

Three Dimensional ◽

Wall Stress ◽

Wide Range ◽

Drag Plate ◽

Rough Boundaries ◽

Single Figure

Using a data correlation for the wall stress associated with very rough boundaries and a semi-empirical calculation method, the shape of boundary layers in exact equilibrium with the roughness beneath them is calculated. A wide range of roughness geometries (two- and three-dimensional elements) is included by the use of equivalent surfaces of equal drag per unit area. Results can be summarized in a single figure which relates the shape factor of the boundary layer (its exponent if it has a power law velocity profile) to the height of the roughness elements and their spacing. New data for one turbulent boundary layer developing over a long fetch of uniform roughness is presented. Wall shear stress, measured directly from a drag plate is combined with boundary layer integral properties to show that the shear stress correlation adopted is reasonably accurate and that the boundary layer is close to equilibrium after passing over a streamwise roughness fetch equal to about 350 times the roughness element height. An example is given of the way in which roughness geometry may be chosen from calculated equilibrium results, for one particular boundary layer thickness and a shape useful for simulating strong atmospheric winds in a wind tunnel.

Download Full-text