Direct Bed Shear Stress Measurements in Bore-Driven Swash and Swash Interactions

2007 ◽  
Author(s):  
Matthew P. Barnes ◽  
Tom E. Baldock
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Stress Measurements

Bed shear stress measurements for vims Sea Carousel

1995 ◽  
Vol 129 (1-2) ◽  
pp. 129-136 ◽  
Author(s):  
Jerome P.-Y. Maa ◽  
C.-H. Lee ◽  
F.J. Chen
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Stress Measurements

scholarly journals Direct bed shear stress measurements in bore-driven swash

2009 ◽  
Vol 56 (8) ◽  
pp. 853-867 ◽  
Author(s):  
M.P. Barnes ◽  
T. O'Donoghue ◽  
J.M. Alsina ◽  
T.E. Baldock
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Stress Measurements

An affordable and reliable device for direct bed shear stress measurements

2021 ◽  
Author(s):  
Stephan Niewerth ◽  
Francisco Núñez-González ◽  
Toni Llull
Keyword(s):  
Shear Stress ◽  
Low Cost ◽  
Large Degree ◽  
Bed Shear Stress ◽  
Flow Conditions ◽  
Stress Measurements ◽  
Boundary Shear ◽  
Shear Plate ◽  
Wide Range ◽  
Boundary Shear Stress

<p>The entrainment and transport of sediment by hydrodynamic mechanisms is strongly related to bed shear stress exerted by flow. Therefore, to quantify sediment transport and to determine sediment incipient motion conditions, accurate estimations of bed shear stress are required. Most of the existing methods used in hydraulics and river engineering to determine bed shear stress are indirect, and are mostly restricted to limited flow conditions or contain a large degree of uncertainty. Although devices to perform direct measurements of boundary shear stress exist, they are normally based on expensive technology. We developed a shear plate for direct shear stress measurements, using relatively low cost components. In this work we present preliminary results of measurements performed with the new shear plate, to characterize the bottom shear stress generated by a ship propeller. The data result in the expected quadratic relation between bed shear stress and jet velocities, and also give evidence of a good reproducibility. We show that the new shear plate appears to be a promising device for reliable measurements of submerged boundary shear stress under a wide range of environments and flow conditions.</p>

The horseshoe vortex and vortex shedding around a vertical wall-mounted cylinder exposed to waves

1997 ◽  
Vol 332 ◽  
pp. 41-70 ◽  
Author(s):  
B. M. Sumer ◽  
N. Christiansen ◽  
J. Fredsøe
Keyword(s):  
Shear Stress ◽  
Vortex Flow ◽  
Vertical Wall ◽  
Horseshoe Vortex ◽  
Wake Flow ◽  
Single Pair ◽  
Bed Shear Stress ◽  
Flume Experiments ◽  
Number Range ◽  
Stress Measurements

This study concerns the flow around the base of a vertical, wall-mounted cylinder - a pile - exposed to waves. The study comprises (i) flow visualization of horseshoe-vortex flow in front of and the lee-wake-vortex flow behind the pile and (ii) bed shear stress measurements around the pile conducted in a wave flume, plus supplementary bed shear stress measurements carried out in an oscillatory-flow water tunnel. The Reynolds number range of the flume experiments is ReD = (2-9) x 103 and that of the tunnel experiments is ReD= 103—5 x 104, in which ReD is based on the pile size. Steadycurrent tests were also carried out for reference. The horseshoe-vortex flow (like leewake-vortex flow) is governed primarily by the Keulegan-Carpenter number, KC. The range of KC was from 0 to about 25 in the flume experiments, and from 4 to 120 in the tunnel experiments. The experiments were conducted mainly with circular piles. The results indicate that no horseshoe vortex exists for KC < 6. The size and lifespan of the horseshoe vortex increase with KC. The influence of the cross-sectional shape of the pile on the horseshoe vortex was investigated. The results show that a square pile with 90° orientation produces the largest horseshoe vortex while that with 45° orientation produces the smallest one, the circular-pile result being between the two. The influence of a superimposed current on the horseshoe vortex was also investigated. The range of the current-to-wave-induced-velocity ratio, Uc/Um, was from 0 to about 0.8. The overall effect of the superimposed current is to increase the size and lifespan of the horseshoe vortex. This effect increases with increasing Uc/Um. Regarding the near-bed lee-wake flow, the flow regimes observed for the two-dimensional free-cylinder case exist for the present case, too, but with one exception: in the present case, no transverse vortex street was observed in the so-called single-pair regime. The results show that the bed shear stress beneath the horseshoe vortex and in the lee-wake area is heavily influenced by KC. The amplification of the bed shear stress with respect to its undisturbed value is maximum (O(4)) at the side edges of the pile, in contrast to what occurs in steady currents where the maximum occurs at an angle of about 45° from the upstream edge of the pile with an amplification of O(10).

Efficiency prediction for storage chambers using computational fluid dynamics

1996 ◽  
Vol 33 (9) ◽  
pp. 163-170 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document