Estimating Bottom Stress in Tidal Boundary Layer from Acoustic Doppler Velocimeter Data

Kim, S.-C.; Friedrichs, Carl T.; Maa, Jerome P.‐Y.; Wright, L. D.

doi:10.1061/(asce)0733-9429(2000)126:6(399)

Cited by 373 publications

(307 citation statements)

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“…When turbulence measurements are available, local mean shear velocity can be determined from the measured Reynolds stress distribution in the constant stress layer where stress within the water column only varies slightly from bottom stress t (Kim et al, 2000). It can be expressed as:…”

Section: Reynolds Stress Methodsmentioning

confidence: 99%

“…This approach is often taken in oceanographic studies (Stapleton and Huntley, 1995). Kim et al (2000) used the same methods as Rowinski et al (2005) and the spectral method in an estuary over a soft mud bottom and recommend further investigating the TKE method based on velocity measurements carried out at two levels. Biron et al (2004) performed laboratory experiments over fine sand, using the same methods and observed that the logarithmic profile methods gave shear velocity estimates that were significantly larger than the remaining methods.…”

Section: Introductionmentioning

confidence: 99%

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Shear velocity estimates in rough‐bed open‐channel flow

Bagherimiyab

Lemmin

2013

Earth Surf Processes Landf

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Shear velocity u * is an important parameter in geophysical flows, in particular with respect to sediment transport dynamics. In this study, we investigate the feasibility of applying five standard methods [the logarithmic mean velocity profile, the Reynolds stress profile, the turbulent kinetic energy (TKE) profile, the wall similarity and spectral methods] that were initially developed to estimate shear velocity in smooth bed flow to turbulent flow over a loose bed of coarse gravel (D 50 = 1Á5 cm) under sub-threshold conditions. The analysis is based on quasi-instantaneous three-dimensional (3D) full depth velocity profiles with high spatial and temporal resolution that were measured with an Acoustic Doppler Velocity Profiler (ADVP) in an open channel. The results of the analysis confirm the importance of detailed velocity profile measurements for the determination of shear velocity in rough-bed flows. Results from all methods fall into a range of AE 20% variability and no systematic trend between methods was observed. Local and temporal variation in the loose bed roughness may contribute to the variability of the logarithmic profile method results. Estimates obtained from the TKE and Reynolds stress methods reasonably agree. Most results from the wall similarity method are within 10% of those obtained by the TKE and Reynolds stress methods. The spectral method was difficult to use since the spectral energy of the vertical velocity component strongly increased with distance from the bed in the inner layer. This made the choice of the reference level problematic. Mean shear stress for all experiments follows a quadratic relationship with the mean velocity in the flow. The wall similarity method appears to be a promising tool for estimating shear velocity under rough-bed flow conditions and in field studies where other methods may be difficult to apply. This method allows for the determination of u * from a single point measurement at one level in the intermediate range (0Á3 < h < 0Á6).

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Section: Reynolds Stress Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shear velocity estimates in rough‐bed open‐channel flow

Bagherimiyab

Lemmin

2013

Earth Surf Processes Landf

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“…An essential part of the field measurement was the determination of the local bed shear stress values. As Kim et al [23] reported in their study, several methods exist to estimate the bed shear stress as a function of the flow conditions. Here, the bed shear stress was estimated based on the turbulent wall law [24] using the time averaged vertical velocity profiles obtained from the fixed boat ADCP measurements and spatio-temporal averaged velocity profiles from the moving boat measurements.…”

Section: Morphological Investigation Based On Flowmeasurementsmentioning

confidence: 99%

Morphological Investigation of a Critical Reach of the Upper Hungarian Danube

Török

Baranya

2017

Period. Polytech. Civil Eng.

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“…15) leading to (18) or from the mean velocity (Eq. 14), which leads to (19) Yet another assumption that applies for the log-layer is the balance between the production rate of turbulent kinetic energy from shear stress (P) and the rate of energy dissipation (ε) by viscous shear (Kim et al 2000;Tennekes and Lumley 1972): (20) Assuming the energy balance, we estimate D T from ε by combining Eqs. 15, 16, 17, and 20:…”

Section: Holtappels and Lorke Turbulent Diffusion In The Bblmentioning

confidence: 99%

Estimating turbulent diffusion in a benthic boundary layer

Holtappels

Lorke

2011

Limnology & Ocean Methods

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In the shallow waters of lakes and the coastal ocean, primary productivity is strongly linked to the mineralization of organic matter in the sediments and thus to the exchange of organic matter, nutrients, and metabolites between sediments and water column (Wollast 1991). The benthic boundary layer (BBL) is the interface between the sediments and the water column. By definition, it is the water layer that is influenced by the friction between the sediment and the moving water column (Dade et al. 2001). The vertical transport of solutes and particulate matter across the BBL is of turbulent nature. Assuming stationary conditions and neglecting the reactivity of the solute in the BBL, the turbulent transport of solutes can be described as quasi diffusive transport according to Fick's law of diffusion: (1) where J denotes the flux, D T is the turbulent diffusivity, and ∂C/∂z is the vertical concentration gradient. Turbulent transport in the BBL is believed to be several orders of magnitude faster compared with molecular diffusion in the sediments. In contrast to molecular diffusion, turbulent diffusion is a function of the flow field and, therefore, varies with the flow velocity in the BBL. There are numerous models in which turbulent diffusivity scales as a function of boundary distance and mean current velocity (Dade et al. 2001). The most common model is the logarithmic law of the wall (i.e., log-law) (von Kármán 1930), verified in various laboratory flume experiments (Pope 2000).However, measurements of turbulent diffusivity in natural boundary flows are scarce. Theoretical constraints from the log-law, such as the linear increase of D T with shear velocity u * and distance to the boundary z (D T = u * kz) suggest that the turbulent transport in the BBL is too fast to limit the oxygen and nutrient fluxes across the sediment-water interface (Boudreau 2001) and, in this respect, turbulent diffusivity may be seen as a parameter of minor interest. We give two reasons why the measurement of turbulent diffusivity in the BBL is of interest. AbstractIn aquatic environments, the benthic boundary layer (BBL) is the transition zone for dissolved solutes that are released or consumed from the sediments. The exchange of solutes between the sediment and the overlying water column depends on the turbulent transport in the benthic boundary layer. In situ measurements of turbulent diffusion in natural benthic boundary layers are scarce and are usually derived from the logarithmic law of the wall (log-law). Based on G. I. Taylor's turbulent diffusion theory, we derived a simple approach to estimate turbulent diffusivity from acoustic Doppler velocimeter (ADV) data. The approach was applied to ADV data collected over a period of 155 h in the BBL of Lake Constance, Germany. The calculated turbulent diffusivities agreed well with those derived in parallel from flux-gradient measurements. In addition, turbulent diffusivities were calculated from several established approaches, including those based on the logarithmic law of the w...

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Estimating Bottom Stress in Tidal Boundary Layer from Acoustic Doppler Velocimeter Data

Cited by 373 publications

References 24 publications

Shear velocity estimates in rough‐bed open‐channel flow

Shear velocity estimates in rough‐bed open‐channel flow

Morphological Investigation of a Critical Reach of the Upper Hungarian Danube

Estimating turbulent diffusion in a benthic boundary layer

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