scholarly journals A NUMERICAL STUDY OF WAVE-CURRENT INTERACTION IN THE BOTTOM BOUNDARY LAYER

2017 ◽  
pp. 17
Author(s):  
Xuan Zhang ◽  
Richard Simons ◽  
Eugeny Buldakov
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Numerical Study ◽  
Bottom Boundary Layer ◽  
Bed Shear Stress ◽  
Bottom Boundary ◽  
Time Histories ◽  
Current Interaction ◽  
Numerical Beach ◽  
Good Agreement

In the present work, a numerical wave-current flume has been developed, based on a standard k-ε model. The numerical flume was 12.86m in length, with a numerical beach at one end of the flume. The Volume of Fluid (VOF) method was used to capture the free surface in the flume. The velocity profile obtained at the test section from the numerical simulation has then been compared with experimental data and good agreement found. Periodic velocities in the bottom boundary layer have been obtained which agree well with the experimental data. The model provides an insight to the changes in bed shear stress time histories that characterise wave current interaction.

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.

Simulations of coastal upwelling on the Sydney Continental Shelf

2000 ◽  
Vol 51 (6) ◽  
pp. 577 ◽  
Author(s):  
Patrick Marchesiello ◽  
Mark T. Gibbs ◽  
Jason H. Middleton
Keyword(s):  
Boundary Layer ◽  
Coastal Upwelling ◽  
Deep Ocean ◽  
Bottom Boundary Layer ◽  
Return Flow ◽  
Pressure Gradients ◽  
Bottom Boundary ◽  
Eastern Australia ◽  
Flow Through ◽  
Good Agreement

Two-dimensional numerical simulations of the response of the coastal waters of Sydney, south-eastern Australia, to idealized upwelling-favourable winds are presented. The spin up of the upwelling circulation is investigated, in particular the structure of the nearshore circulation. The intensity of the final upwelling state is found to be strongly linked to the activation of the return flow through the bottom boundary layer, which is also related to the strength of imposed alongshore pressure gradients. Results from a simulation of upwelling forced by a deep-ocean alongshore-current jet also show the final upwelling state to be weak in comparison with upwelling states produced by the action of the local wind stress. Bottom boundary layer shut-down in the presence of such a forcing jet is also discussed. A simulation of a real upwelling event was also performed and good agreement was found between the simulation and observations from a field experiment performed during summer 1994 in the Sydney coastal ocean.

Large eddy simulation of a stratified boundary layer under an oscillatory current

2009 ◽  
Vol 643 ◽  
pp. 233-266 ◽  
Author(s):  
BISHAKHDATTA GAYEN ◽  
SUTANU SARKAR ◽  
JOHN R. TAYLOR
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Mixed Layer ◽  
Numerical Study ◽  
Bottom Boundary Layer ◽  
Mean Velocity ◽  
Bottom Boundary ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean

A numerical study based on large eddy simulation is performed to investigate a bottom boundary layer under an oscillating tidal current. The focus is on the boundary layer response to an external stratification. The thermal field shows a mixed layer that is separated from the external stratified fluid by a thermocline. The mixed layer grows slowly in time with an oscillatory modulation by the tidal flow. Stratification strongly affects the mean velocity profiles, boundary layer thickness and turbulence levels in the outer region although the effect on the near-bottom unstratified fluid is relatively mild. The turbulence is asymmetric between the accelerating and decelerating stages. The asymmetry is more pronounced with increasing stratification. There is an overshoot of the mean velocity in the outer layer; this jet is linked to the phase asymmetry of the Reynolds shear stress gradient by using the simulation data to examine the mean momentum equation. Depending on the height above the bottom, there is a lag of the maximum turbulent kinetic energy, dissipation and production with respect to the peak external velocity and the value of the lag is found to be influenced by the stratification. Flow instabilities and turbulence in the bottom boundary layer excite internal gravity waves that propagate away into the ambient. Unlike the steady case, the phase lines of the internal waves change direction during the tidal cycle and also from near to far field. The frequency spectrum of the propagating wave field is analysed and found to span a narrow band of frequencies clustered around 45°.

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