The time evolution of rip currents in the nearshore is studied by numerical experiments. generation due to waves propagating and breaking over alongshore variable topography. Our main focus examine significance wave‐current interaction as it affects subsequent development currents, particular when are weak compared wave speed. We describe dynamics using shallow water equations with linear bottom friction forcing parameterized utilizing radiation stress concept. slow variations field, terms...

Suspended sediment concentrations and fluid velocities measured in the swash zone of a high‐energy steep beach were used to investigate importance accelerations suspended transport. Swash flow acceleration was nearly constant at about one‐half downslope gravitational with two important exceptions. We observed strong, short‐lived periods accelerating uprush beginning cycle decelerating backwash end (magnitudes both approximately twice that expected acceleration). Interestingly, spikes load...

The nonlinear dynamics of finite amplitude shear instabilities alongshore currents in the nearshore surf zone over barred beach topography are studied using numerical experiments. These experiments extend recent study Allen et al. [1996], which utilized plane (constant slope) by including shore‐parallel sandbars. model involves finite‐difference solutions to shallow water equations for forced, dissipative, initial‐value problems and employs periodic boundary conditions direction. Effects...

A turbulent Ekman layer created by a steady wind near the water surface is investigated using numerical method of large-eddy simulations. The classical case flow unaffected density stratification and waves revisited to understand internal structure implications traditional assumptions constant effective viscosity '-plane' approximation. series experiments reveals that solution needs correcting even in this case. examination hypothesis confirms its validity but shows varies strongly with...

Turbulent oscillatory flow over sand ripples is examined using three‐dimensional numerical simulations. The model solves the time‐dependent Navier‐Stokes equations on a curvilinear grid in horizontally periodic domain. transitions to turbulence and presence of increases rate dissipation shoaling wave energy compared smooth boundary. influence ripple shape shown alter mean field affect induced drag rates. Shear instabilities near boundary during phases reversal resulting vortex shedding from...

This paper investigates several fundamental aspects of wave-permeable, or “radiation,” lateral boundary conditions. Orlanski (1976) proposed that approximate wave-permeable conditions could be constructed by advecting disturbances out the domain at a phase speed c*, which was to calculated from values prognostic variable near boundary. Rigorous justification for this approach is possible one-dimensional shallow-water flow. It shown, however, floating c* gives poor results in problem because...

A series of numerical experiments is performed to investigate the breaking obliquely incident internal waves propagating towards a bottom slope. The case critical reflection considered, where angle between wave group velocity vector and horizontal matches slope angle. flow evolution found be significantly different from observed previously in simulations normally waves. divergence Reynolds stress zone causes strong along-slope mean current, which changes structure dramatically. does not...

Surf zone currents over irregular bathymetry were observed with GPS‐tracked drifters and modeled the depth‐integrated nonlinear shallow water equations. Trajectories of released in 1–2 m depth sometimes defined rip surf eddies, features that have been difficult to resolve fixed instruments. The drifter‐delineated circulation evolved as tidal level changed during each 4–6 hour deployment. In one case, tide dropped, a shore normal current present for first 2 hours more parallel flow. second on...

A three‐dimensional mixture theory model for flow and sediment transport in the seafloor boundary layer, SedMix3D, simulated over resulting entrainment evolution of rippled beds. SedMix3D treats fluid‐sediment as a continuum varying density viscosity with concentration velocity by Navier‐Stokes equations coupled flux equation mixture. Model validation was performed comparing time‐dependent quantities bulk statistics measurements obtained laboratory under scaled forcing conditions....

phy Oceano s more people and associated infrastructure concentrate along coastal areas, the United States is becoming vulnerable to impact of tropical cyclones.It not surprising, especially after past two hurricane seasons, that hurricanes are costliest natural disasters because migration population towards coast resulting changes in national wealth density or revenue.A better

The nonlinear dynamics of unstable alongshore currents in the nearshore surf zone over variable barred beach topography are studied using numerical experiments. These experiments extend recent studies Allen et al. [1996] and Slinn [1998], which utilized uniform topographies by including sinusoidal variation to shore parallel sandbars. model involves finite difference solutions shallow water equations for forced, dissipative, initial value problems employs periodic boundary conditions...

We present the results of large-eddy simulations (LES) turbulent thermal convection generated by surface cooling in a finite-depth stably stratified horizontal layer with an isothermal bottom surface. The flow is simplified model occurring warm shallow ocean during adverse weather events. Simulations are performed 6 × 1 aspect ratio computational domain using pseudo-spectral Fourier method plane and finite-difference discretization on high-resolution clustered grid vertical direction. A...

The complex coupled interactions between fluid and sandy sediment on the seafloor are simulated with a three-dimensional bottom boundary layer model (SedMix3D) developed from mixture theory. SedMix3D solves unfiltered Navier-Stokes equations for fluid-sediment treated as single continuum effective properties that parameterize sediment-sediment including variable viscosity, bulk hindered settling velocity, shear-induced, empirically calibrated, diffusion term. A flux equation models...

Hurricane storm surge depends on the tidal stage, barometric pressure, Coriolis effect, wind stress, and wave forcing, as well local bathymetry. In past, numerical models, such Sea, Lake, Overland Surges from Hurricanes (SLOSH), neglect forcing components to conserve computational efficiency. However, since hurricane wind, surge, waves are coupled phenomena, numerous situations necessitate inclusion of waves' effects more correctly model surge. This paper describes result a collaborative...

We perform a sensitivity analysis on three-dimensional bottom boundary layer model (SedMix3D) that uses mixture theory to simulate the flow and sediment transport over rippled sand beds. SedMix3D treats fluid-sediment as single continuum with effective properties parameterize sediment-sediment interactions using several closures for phase. The viscosity is one such closure includes three adjustable parameters: intrinsic viscosity, maximum packing concentration of unconsolidated sediment....