Wind effect in turbulence parametrization

Colombini, M.; Stocchino, Alessandro

doi:10.1016/j.advwatres.2005.03.002

Cited by 7 publications

(9 citation statements)

References 21 publications

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“…The latter resembles closely the standard parabolic profile, except that it achieves a finite non-zero value at the free surface. As illustrated by Colombini & Stocchino (2005), the use of such a profile is reasonable when pure wind-driven flows are considered. Therefore, the vertical profile of the dimensionless kinematic eddy viscosity reads denotes the scale of the local friction velocity exerted by the current, considering the flow field over a flat bed with a spatially homogeneous distributed bottom composition.…”

Section: Hydrodynamic Problemmentioning

confidence: 99%

Formation of rhythmic sorted bed forms on the continental shelf: an idealised model

2011

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An idealised model is presented to study the formation of sorted bed forms generated by a wind-driven along-shore current. The study employs a linear stability analysis to describe the time development of perturbations of both bottom composition and bed elevation, superimposed on a flat bed composed of a sediment mixture homogeneously distributed in space. The model considers both bed and suspended loads and takes into account the averaged influence of waves on the flow field and the transport of sediment. The results show that the positive coupling between waves, along-shore current and the erodible heterogeneous bed leads to the amplification of two modes, which exhibit distinct characteristics. A first mode is found to be dominant when moderate hydrodynamic conditions are considered and is primarily amplified by the convergence of sediment transport induced by the changes in the bed elevation. This mode has wavelengths of the order of hundred metres and has coarse (fine) sediments in its troughs (crests). By increasing the height of the waves and/or the strength of the steady current, the second mode can become dominant. This mode is characterised by shorter wavelengths and results from the interaction between the convergence of sediment transport related to changes in the bottom composition and that induced by perturbations of the bed elevation. These bed features can have an up-current or a down-current shift between the centre of the coarse-grained bands and the trough of the bottom wave. Typical growth times of the amplified features are of the order of hundreds of days and the migration rates, in the direction of the along-shore current, range between 0.1 and 10 m per day. A qualitative comparison of the model results with field observations indicates that the generation of two distinct modes provides a possible explanation for the broad range of characteristics of the natural bed features.

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Section: Hydrodynamic Problemmentioning

confidence: 99%

Formation of rhythmic sorted bed forms on the continental shelf: an idealised model

2011

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“…Then, it was possible to detect the influence of the different types of bottom boundary conditions relative to the velocities and to the turbulent quantities. The second one is a wind driven circulation in a closed basin, a well studied problem (see for example [31,32]) characterised by two turbulence scales that are the friction velocities at the bottom u * b and at the free surface u * s . In addition, this benchmark is used to test and compare the different turbulence closures.…”

Section: Description Of the Test Casesmentioning

confidence: 99%

“…The analogy between the wind driven circulation in closed basins and the turbulent Couette-Poiseuille flows has been already discussed in [31], and a detail analysis of the characteristics of these flows can be found in the cited study. In the present context, the wind-driven circulation can be a useful benchmark for the model at hand, owing to the variety of vertical profiles of longitudinal velocity that can be encountered in a simple geometry, such as a closed basin.…”

Section: Description Of the Test Casesmentioning

confidence: 99%

“…In a depth-varying cross-section, vertical profiles of velocities are quite different moving along the transverse direction. Such velocity profiles were studied in detail by [31,32,35,36]. In the shallow regions close to the lateral banks, flow velocity is always positive (i.e., in the wind direction), while a reverse flow occurs in the central region.…”

Section: Wind Driven Trapezoidal Closed Basinmentioning

confidence: 99%

See 1 more Smart Citation

A Reasoned Comparison between Two Hydrodynamic Models: Delft3D-Flow and ROMS (Regional Oceanic Modelling System)

Putzu

Enrile

Besio

et al. 2019

JMSE

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Useful information, such as water levels, currents, salinity and temperature dynamics in water bodies, are obtained through numerical models in order to pursue scientific research or consultancy. Model validation dates back long ago, since such models started to be developed in the 1960s. Despite their usefulness and reliability in complex situations, some issues related to well-known benchmarks are still present. This work aims to analyse in detail the behaviour of the velocity profile, vertical eddy viscosity and tangential stresses at the bed in two cases of free surface flows; namely: uniform flow in an inclined rectangular channel and a wind-induced circulation in a closed basin. Computational results strongly depend on the turbulence closure model employed and a reasoned comparison is necessary to highlight possible improvements of these models. The strong differences that arise are deeply analysed in this work.

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“…In a more complete implementation, higher order interpolation methods should be used in the semi-Lagrangian scheme (see, e.g., Baudisch et al, 2006), along with an appropriate horizontal viscosity model. On the other hand, the algebraic eddy viscosity model derived in Colombini and Stocchino (2005) has been employed for the vertical viscosity terms.…”

Section: The Hydrodynamic Model and Its Numerical Discretizationmentioning

confidence: 99%

A coupled ecological–hydrodynamic model for the spatial distribution of sessile aquatic species in thermally forced basins

Mari

Biotto

Decoene

et al. 2009

Ecological Modelling

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Wind effect in turbulence parametrization

Cited by 7 publications

References 21 publications

Formation of rhythmic sorted bed forms on the continental shelf: an idealised model

Formation of rhythmic sorted bed forms on the continental shelf: an idealised model

A Reasoned Comparison between Two Hydrodynamic Models: Delft3D-Flow and ROMS (Regional Oceanic Modelling System)

A coupled ecological–hydrodynamic model for the spatial distribution of sessile aquatic species in thermally forced basins

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