General velocity formula of boundary layer above mobile sediment bed induced by asymmetric waves

2021 ◽  
Vol 36 (2) ◽  
pp. 255-267
Author(s):  
Xin Chen ◽  
Minghong Chen
Keyword(s):  
Boundary Layer ◽  
Sediment Bed ◽  
General Velocity

scholarly journals Deep-water sediment wave formation: linear stability analysis of coupled flow/bed interaction

2011 ◽  
Vol 680 ◽  
pp. 435-458 ◽  
Author(s):  
L. LESSHAFFT ◽  
B. HALL ◽  
E. MEIBURG ◽  
B. KNELLER
Keyword(s):  
Boundary Layer ◽  
Stability Analysis ◽  
Internal Wave ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Stokes Equations ◽  
Wave Mode ◽  
Bottom Current ◽  
Field Observations ◽  
Sediment Bed

A linear stability analysis is carried out for the interaction of an erodible sediment bed with a sediment-laden, stratified flow above the bed, such as a turbidity or bottom current. The fluid motion is described by the full, two-dimensional Navier–Stokes equations in the Boussinesq approximation, while erosion is modelled as a diffusive flux of particles from the bed into the fluid. The stability analysis shows the existence of both Tollmien–Schlichting and internal wave modes in the stratified boundary layer. For the internal wave mode, the stratified boundary layer acts as a wave duct, whose height can be determined analytically from the Brunt–Väisälä frequency criterion. Consistent with this criterion, distinct unstable perturbation wavenumber regimes exist for the internal wave mode, which are associated with different numbers of pressure extrema in the wall-normal direction. For representative turbidity current parameters, the analysis predicts unstable wavelengths that are consistent with field observations. As a key condition for instability to occur, the base flow velocity boundary layer needs to be thinner than the corresponding concentration boundary layer. For most of the unstable wavenumber ranges, the phase relations between the sediment bed deformation and the associated wall shear stress and concentration perturbations are such that the sediment waves migrate in the upstream direction, which again is consistent with field observations.

scholarly journals Aeolian and subaqueous bedforms in shear flows

2013 ◽  
Vol 371 (2004) ◽  
pp. 20120364 ◽  
Author(s):  
Bruno Andreotti ◽  
Philippe Claudin
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Water Depth ◽  
Size Effects ◽  
Finite Size ◽  
Linear Instability ◽  
Laboratory Measurements ◽  
Finite Size Effects ◽  
Sediment Bed

A sediment bed sheared by an unbounded flow is unconditionally unstable towards the growth of bedforms called ripples under water and dunes in the aeolian case. We review here the dynamical mechanisms controlling this linear instability, putting the emphasis on testing models against field and laboratory measurements. We then discuss the role of nonlinearities and the influence of finite size effects, namely the depth of the atmospheric boundary layer in the aeolian case and the water depth in the case of rivers.

Effects of continental boundary layer evolution, convection, turbulence and entrainment, on aerosol formation

Tellus B ◽  
2001 ◽  
Vol 53 (4) ◽  
pp. 441-461 ◽  
Author(s):  
E. D. NILSSON ◽  
Ü. RANNIK ◽  
M. KULMALA ◽  
G. BUZORIUS ◽  
C. D. O'DOWD
Keyword(s):  
Boundary Layer ◽  
Aerosol Formation

Characteristics of the Night and Day Time Atmospheric Boundary Layer at Dome C, Antarctica

2007 ◽  
Vol 25 ◽  
pp. 49-55 ◽  
Author(s):  
S. Argentini ◽  
I. Pietroni ◽  
G. Mastrantonio ◽  
A. Viola ◽  
S. Zilitinchevich
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Night And Day
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