A perturbation approach to large eddy simulation of wave-induced bottom boundary layer flows

2011 ◽  
Vol 68 (12) ◽  
pp. 1574-1604 ◽  
Author(s):  
Jeffrey C. Harris ◽  
Stéphan T. Grilli
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Bottom Boundary Layer ◽  
Perturbation Approach ◽  
Boundary Layer Flows ◽  
Bottom Boundary ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Wave Induced

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°.

A grid nesting method for large-eddy simulation of planetary boundary-layer flows

1996 ◽  
Vol 80 (1-2) ◽  
pp. 167-202 ◽  
Author(s):  
Peter P. Sullivan ◽  
James C. McWilliams ◽  
Chin-Hoh Moeng
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Planetary Boundary Layer ◽  
Boundary Layer Flows ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Grid Nesting
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