scholarly journals Surf zone cross-shore boundary layer velocity asymmetry and skewness: An experimental study on a mobile bed

2013 ◽  
Vol 118 (4) ◽  
pp. 2188-2200 ◽  
Author(s):  
C. Berni ◽  
E. Barthélemy ◽  
H. Michallet
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Surf Zone ◽  
Mobile Bed ◽  
Layer Velocity

scholarly journals ASYMMETRY AND SKEWNESS IN THE BOTTOM BOUNDARY LAYER : SMALL SCALE EXPERIMENTS AND NUMERICAL MODEL

2012 ◽  
Vol 1 (33) ◽  
pp. 25
Author(s):  
Céline Berni ◽  
Leandro Suarez ◽  
Hervé Michallet ◽  
Eric Barthélemy
Keyword(s):  
Boundary Layer ◽  
Linear Relation ◽  
Surf Zone ◽  
Free Stream ◽  
Small Scale ◽  
Wave Flume ◽  
Random Forcing ◽  
Mobile Bed ◽  
Layer Analysis ◽  
Wave Boundary

This study investigates the non-linearities of wave boundary layers in the surf zone. It mainly focuses on the acceleration skewness or asymmetry. Experiments [e.g. Grasso et al., 2011] show that asymmetry influences the sediment transport. Its influence lies in the fact that asymmetry in velocity (acceleration skewness) tends to transform into velocity skewness within the boundary layer. Analysis by Henderson et al. [2004] predicts a linear relation between Skb/Sk∞ and As∞/Sk∞ where Skb is the dimensionless skewness near the bed, Sk∞ the free-stream dimensionless skewness and As∞ the free-stream dimensionless asymmetry. Numerous experiments were carried out in the LEGI wave flume over a mobile bed composed of lightweight sediments. The quasi-random forcing is a repetition of 2 concatenated bichromatic wave packets. Vertical profiles of velocity are measured in the surf zone. A clear linear relation is shown between these two ratios. The experimental results are compared with the numerical results. A linear relation between skewness and asymmetry is also obtained.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

The Influence of Boundary Layer Velocity Gradients and Bed Proximity on Vortex Shedding From Free Spanning Pipelines

1984 ◽  
Vol 106 (1) ◽  
pp. 70-78 ◽  
Author(s):  
A. J. Grass ◽  
P. W. J. Raven ◽  
R. J. Stuart ◽  
J. A. Bray
Keyword(s):  
Boundary Layer ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Combined Effects ◽  
Maximum Increase ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Layer Velocity ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

The paper summarizes the results of a laboratory study of the separate and combined effects of bed proximity and large velocity gradients on the frequency of vortex shedding from pipeline spans immersed in the thick boundary layers of tidal currents. This investigation forms part of a wider project concerned with the assessment of span stability. The measurements show that in the case of both sheared and uniform approach flows, with and without velocity gradients, respectively, the Strouhal number defining the vortex shedding frequency progressively increases as the gap between the pipe base and the bed is reduced below two pipe diameters. The maximum increase in vortex shedding Strouhal number, recorded close to the bed in an approach flow with large velocity gradients, was of the order of 25 percent.

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