Experimental investigation of sediment resuspension beneath internal solitary waves of depression

Aghsaee, Payam; Boegman, Leon

doi:10.1002/2014jc010401

Cited by 52 publications

(42 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[] provided additional insight toward the capacity of the instability to drive resuspension, as well as, simulations by Stastna and Lamb []. Aghsaee and Boegman [] parametrized the ISW‐induced resuspension by considering vertical velocity bursts, occurring behind the wave during propagation. Their approximation of the ISW‐induced shear stress is expressed as,

τ_{I S W} = ρ_{2} c_{o}^{2} {[0.09 ln (R e_{I S W}) - 0.44]}^{2},

where c o is the linear wave phase speed in a two‐layer continuously stratified water column

(c_{o}^{2} = Δ ρ g h_{1} h_{2} / (ρ_{o} H))

and Re ISW is the momentum thickness Reynolds number based on the wave‐induced bottom boundary layer (

R e_{I S W} = | U_{2} | \sqrt{L_{W} / (ν (| U_{2} | + c)}

where ν is the kinematic viscosity and U 2 is the horizontal ISW‐induced velocity at the bottom layer).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Bed failure induced by internal solitary waves

2017

View full text Add to dashboard Cite

The pressure field inside a porous bed induced by the passage of an Internal Solitary Wave (ISW) of depression is examined using high‐accuracy numerical simulations. The velocity and density fields are obtained by solving the Dubreil‐Jacotin‐Long Equation, for a two‐layer, continuously stratified water column. The total wave‐induced pressure across the surface of the bed is computed by vertically integrating for the hydrostatic and nonhydrostatic contributions. The bed is assumed to be a continuum composed of either sand or silt, with a small amount of trapped gas. Results show variations in pore‐water pressure penetrating deeper into more conductive materials and remaining for a prolonged period after the wave has passed. In order to quantify the potential for failure, the vertical pressure gradient is compared against the buoyant weight of the bed. The pressure gradient exceeds this weight for weakly conductive materials. Failure is further enhanced by a decrease in bed saturation, consistent with studies in surface‐wave induced failure. In deeper water, the ISW‐induced pressure is stronger, causing failure only for weakly conductive materials. The pressure associated with the free‐surface displacement that accompanies ISWs is significant, when the water depth is less than 100 m, but has little influence when it is greater than 100 m, where the hydrostatic pressure due to the pycnocline displacement is much larger. Since the pore‐pressure gradient reduces the specific weight of the bed, results show that particles are easier for the flow to suspend, suggesting that pressure contributes to the powerful resuspension events observed in the field.

show abstract

τ_{I S W} = ρ_{2} c_{o}^{2} {[0.09 ln (R e_{I S W}) - 0.44]}^{2},

where c o is the linear wave phase speed in a two‐layer continuously stratified water column

(c_{o}^{2} = Δ ρ g h_{1} h_{2} / (ρ_{o} H))

and Re ISW is the momentum thickness Reynolds number based on the wave‐induced bottom boundary layer (

R e_{I S W} = | U_{2} | \sqrt{L_{W} / (ν (| U_{2} | + c)}

where ν is the kinematic viscosity and U 2 is the horizontal ISW‐induced velocity at the bottom layer).…”

Section: Discussionmentioning

confidence: 99%

“…Applying equation to the nonlinear internal waves observed by Quaresma et al . [], Aghsaee and Boegman [] estimated the ISW‐induced shear stress with equation to be 8.979 Pa or

8.803 \times 10^{- 3}

m 2 s – 2 .…”

Section: Discussionmentioning

confidence: 99%

Bed failure induced by internal solitary waves

2017

View full text Add to dashboard Cite

show abstract

“…The NLIW life cycle (i.e., evolution, propagation, shoaling, and breaking) has been well studied in two‐dimensions at field‐scale (large Reynolds number) [e.g., Vlasenko and Hutter , ; Bourgault et al ., ; Lamb and Farmer , ] and laboratory‐scale [e.g., Horn et al ., ; Boegman et al ., ]. However, NLIW dynamics are fundamentally three‐dimensional (3‐D) at turbulent scales [ Fringer and Street , ; Arthur and Fringer , ; Aghsaee and Boegman , ] and the basin‐scale [ Boegman and Dorostkar , ; de la Fuente et al ., ], where they are locally influenced by topography [ Vlasenko and Stashchuk , ; Zhang et al ., ]. Despite this three‐dimensionality, computational demands [e.g., Aghsaee et al ., ] have limited most field‐scale modeling of NLIWs to two‐dimensions (2‐D) in narrow lakes and tidal flows [e.g., Vlasenko and Hutter , ; Scotti et al ., ; Lamb and Farmer , ; Bourgault et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional simulation of high‐frequency nonlinear internal wave dynamics in Cayuga Lake

2017

Self Cite

View full text Add to dashboard Cite

Three‐dimensional (3‐D) hydrostatic and nonhydrostatic versions of the MITgcm were applied to simulate the dynamics of the internal wave field (basin‐scale seiches, nonlinear surges, and high‐frequency nonlinear internal waves, NLIWs) in Cayuga Lake, NY. The simulations were performed using up to 226 million computational cells with several horizontal grid resolutions, varying from 450 × 450 m to 22 × 22 m. Vertical grid spacing was not varied and ranged from 0.5 to 2.95 m. The 22 × 22 m nonhydrostatic grid reproduced qualitatively the formation, propagation, and shoaling of observed NLIWs using >10 grid points along the wavelength and a grid lepticity λ of O(1). This ensured, respectively, that the waves were not aliased and physical dispersion predominated over numerical dispersion. Using a sensitivity analysis, we generalize that correctly simulating NLIWs in real domains, using second‐order discretization, requires grid resolutions that are an order of magnitude smaller than the wavelength and amplitude with λ ∼ 2; consistent with published work on idealized domains. Local gyre‐like circulation was simulated, near midbasin headlands, and transverse shoaling of NLIW packets on lateral boundaries was associated with topographic reflection and refraction, in agreement with published field observations from estuaries, which show NLIW propagation in long narrow quasi‐2‐D systems (e.g., Finger Lakes, lochs, fjords, estuaries, and straits) is fundamentally 3‐D. These results, therefore, help fill the gap in understanding and correctly modeling the multiscale 3‐D dynamics of NLIWs in complex natural systems.

show abstract

“…Some observational and experimental studies suggest internal wave induced pumping of sediments high into the water column. 8,9 Other computational and laboratory studies have worked to evaluate a critical wave amplitude and Reynolds number required for vortex shedding. 4,10 In particular, the laboratory experiments by Carr et al, 10 which involved internal solitary waves of depression, found qualitative agreement in the behaviour of vortex shedding with the two-dimensional numerical results of Diamessis and Redekopp.…”

Section: Introductionmentioning

confidence: 99%

“…Bottom shear stress calculations suggested that the strongest nonlinear internal waves were capable of suspending sediment. The laboratory experiments of Aghsaee and Boegman 9 show that the vertical velocities induced by bursting motions in the boundary layer are important factors in sediment resuspension.…”

Section: Introductionmentioning

confidence: 99%

Topographically generated internal waves and boundary layer instabilities

2015

View full text Add to dashboard Cite

Flow over topography has been shown to generate finite amplitude internal waves upstream, over the topography and downstream. Such waves can interact with the viscous bottom boundary layer to produce vigorous instabilities. However, the strength and size of such instabilities depends on whether viscosity significantly modifies the wave generation process, which is usually treated using inviscid theory in the literature. In this work, we contrast cases in which boundary layer separation profoundly alters the wave generation process and cases for which the generated internal waves largely match inviscid theory. All results are generated using a numerical model that simulates stratified flow over topography. Several issues with using a wave-based Reynolds number to describe boundary layer properties are discussed by comparing simulations with modifications to the domain depth, background velocity, and viscosity. For hill-like topography, three-dimensional aspects of the instabilities are also discussed. Decreasing the Reynolds number by a factor of four (by increasing the viscosity), while leaving the primary two-dimensional instabilities largely unchanged, drastically affects their three-dimensionalization. Several cases at the laboratory scale with a depth of 1 m are examined in both two and three dimensions and a subset of the cases is scaled up to a field scale 10-m deep fluid while maintaining similar values for the background current and viscosity. At this scale, increasing the viscosity by an order of magnitude does not significantly change the wave properties but does alter the wave’s interaction with the bottom boundary layer through the bottom shear stress. Finally, two subcritical cases for which disturbances are able to propagate upstream showcase a set of instabilities forming on the upstream slope of the elevated topography. The time scale over which these instabilities develop is related to but distinct from the advective time scale of the waves. At a non-dimensional time when instabilities have formed in the field scale case, no instabilities have yet formed in the lab scale case.

show abstract

Experimental investigation of sediment resuspension beneath internal solitary waves of depression

Cited by 52 publications

References 38 publications

Bed failure induced by internal solitary waves

Bed failure induced by internal solitary waves

Three‐dimensional simulation of high‐frequency nonlinear internal wave dynamics in Cayuga Lake

Topographically generated internal waves and boundary layer instabilities

Contact Info

Product

Resources

About