Initiation of motion and scour burial of objects underwater

Rennie, Sarah E.; Brandt, Alan; Friedrichs, Carl T.

doi:10.1016/j.oceaneng.2016.12.029

Cited by 19 publications

(13 citation statements)

References 21 publications

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“…plane bed‐type streams; Simons and Richardson, 1966), local scour incision can functionally be determined by:

d_{s} = f ((), d_{w}, U_{m}, ρ, ν, g, B, h_{o}, w_{o}, {le}_{o}, italicMb, D_{50}, ρ_{s}, σ_{G}, U_{c}, d_{sed}, t)

where d s is local scour depth [L], ρ is water density [ML −3 ], B is channel cross‐section [L], le o is length of obstacle in streamwise direction [L], Mb is an indicator for the mobility of a boulder‐like obstruction, due to tilting into the scoured depression which limits further evolution of local scouring and induces equilibrium more quickly (e.g. Truelsen et al ., 2005; Friedrich et al ., 2016; Euler et al ., 2017; Rennie et al ., 2017), ρ s is sediment density and d sed is the thickness of the alluvial layer [L].…”

Section: Review Of Boundary Conditions Of Morphodynamic Processes At mentioning

confidence: 99%

Boundary condition control of fluvial obstacle mark formation – framework from a geoscientific perspective

Schlömer

Herget

Euler

2020

Earth Surf Processes Landf

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Obstacle marks are sedimentary bedforms, typically composed of an upstream local scour hole and a downstream sediment accumulation in the vicinity of an obstruction that is exposed to a current. However, specific morphologies are variable in fluvial, coastal and submarine environments. Although obstacle marks and the phenomenon of local scouring are subject to different scientific disciplines, the objectives of investigations are rather incoherent and no systematic framework for analysing and evaluating boundary condition control exists yet, especially concerning limited knowledge of the cause and effect relationship of obstacle mark formation at instream boulders or vegetation elements in variable environmental conditions. Thus, a parameter framework is developed which identifies a spectrum of extrinsic and intrinsic boundary conditions that control the major process dynamics of obstacle mark formation. The framework is composed of dimensionless control parameters that are separated by a hierarchical order regarding their significance for obstacle mark formation. Primary control parameters determine the geometrical scale of flow field at the obstacle, and therefore control the potential maximum size of the obstacle. Secondary control parameters affect the dynamics of the flow field in geometrical scale and limit the potential maximum size of the emerging sedimentary structure if thresholds are crossed. The framework is supposed to be a foundation for subsequent quantification and determination of thresholds by systematic laboratory studies. To elucidate this, flume-based research is presented, evaluating the influence of different flow levels at boulder-like obstacles of different shapes. The results show that obstacle mark dimensions were maximized at shallow flow depths compared to obstacle dimensions, while deep flows at submerged boulder-like obstructions caused considerably smaller obstacle marks. In interdependency with a rounded and more streamlined obstacle shape, deep flows even cause a deviation of morphology if the flow depth above an obstacle exceeds 1.6 times the obstacle's dimensions.

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“…plane bed‐type streams; Simons and Richardson, 1966), local scour incision can functionally be determined by:

d_{s} = f ((), d_{w}, U_{m}, ρ, ν, g, B, h_{o}, w_{o}, {le}_{o}, italicMb, D_{50}, ρ_{s}, σ_{G}, U_{c}, d_{sed}, t)

Section: Review Of Boundary Conditions Of Morphodynamic Processes At mentioning

confidence: 99%

Boundary condition control of fluvial obstacle mark formation – framework from a geoscientific perspective

Schlömer

Herget

Euler

2020

Earth Surf Processes Landf

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“…is crucial for scour burial of motionless object and in turn for prediction of the percentage burial parameter pB(t) = B/D [15]- [16]. Here, f is the wave friction factor [23], ρs the sediment grain density, and d50 the medium sand As pointed in [23], the equilibrium percentage burial pB,eq for motionless cylinders induced by scour tends to increase as θsed increases.…”

Section: Object Scour Modelmentioning

confidence: 99%

“…Model output from Delft3D provides the neighboring environment required parameters to the 6-DoF model to predict a munition's burial and mobility. Under the sponsorship of SERDP, experimental [13][14] and analytical [15][16] studies focus on the determination of the conditions that determine the onset of a specific and important motion, i.e., roll of munition around its main axis, both on a hard surface and on a sand bed in the presence of concurrent scour burial.…”

Section: Introductionmentioning

confidence: 99%

Coupled Delft3D-Object Model to Predict Mobility and Burial of Munition on Sandy Floor

Chu¹,

Vs²,

Chen³

2021

Preprint

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Coupled Delft3D-object model has been developed to predict object’s mobility and burial on sandy seafloor. The Delft3D model is used to predict seabed environment such as currents, waves (peak period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) object‘s physical parameters such as diameter, length, mass, and rolling moment, (b) dynamics of rolling cylinder around its major axis, and (c) empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 23 May 2013 off the coast of Panama City, Florida funded by the Department of Defense Strategic Environmental Research and Development Program. The experimental data contain both objects’ mobility using sector scanning and pencil beam sonars and simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly show the model capability.

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“…Previous experimental observations [9]- [11] and statistical modeling [12] focus on the determination of the conditions that initiate motion, specifically, the roll of a munition around its principle axis, both on a hard surface and on a sand bed in the presence of concurrent scour burial. Mobility of an object on the seafloor is characterized by the balance between the destabilizing hydrodynamics and the stabilizing weight of the object [13], [14]. The Shields parameter for object percentage burial θ opb is estimated using the size and density of the object as well as the local velocity perpendicular to its main axis, U.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Mobility and Burial of Objects on Sandy Seafloor

Chu

Fan

Calantoni

et al. 2022

IEEE J. Oceanic Eng.

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A numerical model was developed to predict mobility and burial of seafloor cylindrical objects. The model contains four components: 1) object's physical parameters such as diameter, length, mass, and rolling moment; 2) dynamics of rolling cylinder around its major axis; 3) empirical sediment scour model; and 4) seabed environmental characteristics such as currents, waves (peak period, significant wave height), sediment density, and medium sediment grain size. Under the sponsorship of the Department of Defense Strategic Environmental Research and Development Program, a field experiment was conducted from April 21 to May 23, 2013 off the coast of Panama City, FL, USA to measure both objects' mobility using sector scanning and pencil beam sonars and simultaneous environmental time-series data of the boundary layer hydrodynamics and sediment transport conditions for driving mobility. Comparison between modeled and observed data shows the model capability. Future work needs to consider more realistic object shapes and motions such as pitch and yaw, and wavy seabed. Index Terms-Equilibrium burial percentage, munitions mobility and burial, object mobility model, object shields parameter, sediment shields parameter, sediment supporting point. NOMENCLATURE(a 1 , a 2 , a 3 ) Empirical coefficients (25). BObject burial depth (m) [( 8), ( 11), ( 12), ( 14), (15a), ( 17), ( 28)]. b Depth of rotation axis in sediment (m) [(2), (8), (11), (14), (15a), (17)]. (c 1 , c 2 ) Coefficients in e-folding time scale for scour burial [see (27)]. (C d , C l ) (Drag, Lift) Coefficients [(12), (13)].

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Initiation of motion and scour burial of objects underwater

Cited by 19 publications

References 21 publications

Boundary condition control of fluvial obstacle mark formation – framework from a geoscientific perspective

Boundary condition control of fluvial obstacle mark formation – framework from a geoscientific perspective

Coupled Delft3D-Object Model to Predict Mobility and Burial of Munition on Sandy Floor

Prediction of Mobility and Burial of Objects on Sandy Seafloor

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