Two-dimensional instability of the bottom boundary layer under a solitary wave

2015 ◽  
Vol 27 (4) ◽  
pp. 044101 ◽  
Author(s):  
Mahmoud M. Sadek ◽  
Luis Parras ◽  
Peter J. Diamessis ◽  
Philip L.-F. Liu
Keyword(s):  
Boundary Layer ◽  
Solitary Wave ◽  
Bottom Boundary Layer ◽  
Two Dimensional ◽  
Bottom Boundary ◽  
Dimensional Instability

Validation of a new generation system for bottom boundary layer beneath solitary wave

2012 ◽  
Vol 59 (1) ◽  
pp. 46-56 ◽  
Author(s):  
Hitoshi Tanaka ◽  
Bambang Winarta ◽  
Suntoyo ◽  
Hiroto Yamaji
Keyword(s):  
Boundary Layer ◽  
Solitary Wave ◽  
Bottom Boundary Layer ◽  
Generation System ◽  
Bottom Boundary ◽  
New Generation

Boundary-layer flow and bed shear stress under a solitary wave: revision

2014 ◽  
Vol 753 ◽  
pp. 554-559 ◽  
Author(s):  
Yong Sung Park ◽  
Joris Verschaeve ◽  
Geir K. Pedersen ◽  
Philip L.-F. Liu
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Solitary Wave ◽  
Boundary Layer Flow ◽  
Bottom Boundary Layer ◽  
Bed Shear Stress ◽  
Bottom Boundary ◽  
Layer Flow

AbstractWe address two shortcomings in the article by Liu, Park & Cowen (J. Fluid Mech., vol. 574, 2007, pp. 449–463), which gave a theoretical and experimental treatise of the bottom boundary-layer under a solitary wave.

Two-dimensional vortex structures in the bottom boundary layer of progressive and solitary waves

2013 ◽  
Vol 728 ◽  
pp. 340-361 ◽  
Author(s):  
Pietro Scandura
Keyword(s):  
Boundary Layer ◽  
Solitary Waves ◽  
Small Amplitude ◽  
Flow Instability ◽  
Vortex Structures ◽  
Bottom Boundary Layer ◽  
Two Dimensional ◽  
Bottom Boundary ◽  
Vortex Layer ◽  
Vortex Tubes

AbstractThe two-dimensional vortices characterizing the bottom boundary layer of both progressive and solitary waves, recently discovered by experimental flow visualizations and referred to as vortex tubes, are studied by numerical solution of the governing equations. In the case of progressive waves, the Reynolds numbers investigated belong to the subcritical range, according to Floquet linear stability theory. In such a range the periodic generation of strictly two-dimensional vortex structures is not a self-sustaining phenomenon, being the presence of appropriate ambient disturbances necessary to excite certain modes through a receptivity mechanism. In a physical experiment such disturbances may arise from several coexisting sources, among which the most likely is roughness. Therefore, in the present numerical simulations, wall imperfections of small amplitude are introduced as a source of disturbances for both types of wave, but from a macroscopic point of view the wall can be regarded as flat. The simulations show that even wall imperfections of small amplitude may cause flow instability and lead to the appearance of vortex tubes. These vortices, in turn, interact with a vortex layer adjacent to the wall and characterized by vorticity opposite to that of the vortex tubes. In a first stage such interaction gives rise to corrugation of the vortex layer and this affects the spatial distribution of the wall shear stress. In a second stage the vortex layer rolls up and pairs of counter-rotating vortices are generated, which leave the bottom because of the self-induced velocity.

scholarly journals TURBULENCE APPEARANCE AT THE BOTTOM OF A SOLITARY WAVE

2012 ◽  
Vol 1 (33) ◽  
pp. 17
Author(s):  
Paolo Blondeaux ◽  
Jan Pralits ◽  
Giovanna Vittori
Keyword(s):  
Boundary Layer ◽  
Stability Analysis ◽  
Solitary Wave ◽  
Threshold Value ◽  
Bottom Boundary Layer ◽  
Laminar Regime ◽  
Bottom Boundary ◽  
Local Water ◽  
The Stability ◽  
Theoretical Results

The conditions leading to transition and turbulence appearance at the bottom of a solitary wave are determined by means of a linear stability analysis of the laminar flow in the bottom boundary layer. The ratio between the wave amplitude and the thickness of the viscous bottom boundary layer is assumed to be large and a 'momentary' criterion of instability is used. The results obtained show that the laminar regime becomes unstable, during the decelerating phase, if the height of the wave is larger than a threshold value which depends on the ratio between the boundary layer thickness and the local water depth. A comparison of the theoretical results with the experimental measurements of Sumer et al. (2010) seems to support the stability analysis.

scholarly journals NEAR BOTTOM VELOCITIES IN WAVES WITH A CURRENT; ANALYTICAL AND NUMERICAL COMPUTATIONS

1984 ◽  
Vol 1 (19) ◽  
pp. 79 ◽  
Author(s):  
W.G.M. Van Kesteren ◽  
W.T. Bakker
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Bottom Friction ◽  
Bottom Boundary Layer ◽  
Two Dimensional ◽  
Layer Model ◽  
Bottom Boundary ◽  
Waves And Currents ◽  
A Current ◽  
Bottom Velocities

In this paper, starting from the Prandtl hypothesis a three-dimensional numerical bottom boundary layer model has been developed, which allows to calculate bottom friction by a combination of waves and currents. The model has been compared with two-dimensional analytical computations which gave similar results. The bottom friction values found are comparable to the ones, found by Lundgren (1972), however in the most relevant cases somewhat less. Furthermore in the two-dimensional case the model has been compared with measurements of Bakker and Van Doom (1978). With respect to the oscillatory motion, still some minor deviations occur between theory and measurements, due to deficiencies of the Prandtl theory.

scholarly journals Bottom Boundary Layer beneath Solitary Wave Motion

2009 ◽  
Vol 65 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Mohammad BAGUS ADITYAWAN ◽  
Bambang WINARTA ◽  
Hitoshi TANAKA ◽  
Hiroto YAMAJI
Keyword(s):  
Boundary Layer ◽  
Solitary Wave ◽  
Wave Motion ◽  
Bottom Boundary Layer ◽  
Bottom Boundary
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