Lagrangian mixing in straight compound channels

Stocchino, Alessandro; Besio, Giovanni; Angiolani, Sonia; Brocchini, Maurizio

doi:10.1017/s0022112011000127

Cited by 25 publications

(57 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As suggested by Nezu et al [1999] and verified by Stocchino and Brocchini [2010], the dynamics of the flow field and, hence, of the vorticity, strongly depends on the flow characteristics in terms of the flow‐depth ratio r h , between the depth in the main channel (

h_{mc}^{*}

) and the depth in the floodplains (

h_{fp}^{*}

) as first introduced by Shiono and Knight [1991] and later modified by Nezu et al [1999]. In a more recent contribution, Stocchino et al [2011] investigated the different dispersion regimes occurring in compound channel flows and highlighting the dependence of mixing both on the depth ratio r h and on the subcritical/supercritical character of the flow, i.e., on the Froude number ( Fr ).…”

Section: Introductionmentioning

confidence: 91%

Transversal and longitudinal mixing in compound channels

Besio¹,

Stocchino²,

Angiolani³

et al. 2012

Water Resources Research

View full text Add to dashboard Cite

[1] An experimental campaign, based on particle image velocimetry (PIV) measurements of free-surface velocities, forms the basis for an analysis of the mixing processes which occur in a compound-channel flow. The flow mixing is characterized in terms of Lagrangian statistics (absolute dispersion and diffusivity) and of the related mean flow characteristics. Mixing properties strongly depend on the ratio r h between the main channel flow depth (h Ã mc ) and the floodplain depth (h Ã fp ), and three flow classes can be identified, namely shallow, intermediate, and deep flows. In the present study the large time asymptotic behavior of the mixing characteristics is analyzed in terms of the absolute diffusivity in order to characterize typical values of longitudinal and transversal diffusivity coefficients. Various sets of experiments, which cover a wide range of the governing physical parameters, have been performed and the asymptotic values of the absolute diffusivity have been evaluated. The results are then compared with several studies of flow dispersion for both the longitudinal diffusivity coefficient and the transversal turbulent mixing coefficient. The present results highlight a stronger dependence of such coefficients with the flow-depth ratio than with the flow regime (Froude number).

show abstract

h_{mc}^{*}

) and the depth in the floodplains (

h_{fp}^{*}

Section: Introductionmentioning

confidence: 91%

Transversal and longitudinal mixing in compound channels

Besio¹,

Stocchino²,

Angiolani³

et al. 2012

Water Resources Research

View full text Add to dashboard Cite

show abstract

“…Spanwise and vertical velocities at interface show the maximum in magnitude at the junction of the main channel and the floodplain in both the channels. However, in symmetric channel, the spanwise interface velocity at the junction is of opposite direction indicating the presence of two horizontal vortices of equal strength but opposite in nature (Stocchino et al 2011). Similarly, a horizontal vortex is seen to be formed near the junction in asymmetric channel also.…”

Section: Spanwise and Vertical Flow Velocity At Interface (V 0 W 0 )mentioning

confidence: 89%

Development of Two-layered model for compound open-channel flow

Sinha

Das

Patel

et al. 2014

ISH Journal of Hydraulic Engineering

View full text Add to dashboard Cite

Present study deals with the development of two-dimensional two-layered model for straight compound open-channel flow using Smagorinsky-based subgrid-scale turbulence model, based on large eddy simulation approach. The two-layer depth averaged governing equations are solved using finite volume method based on MacCormack predictor-corrector explicit scheme. Model results for symmetric and asymmetric straight compound channel flows are verified with the available numerical and experimental data. Variations of flow variables in symmetric and asymmetric straight compound channels in terms of shear stress distributions and spanwise and vertical velocities are analyzed at the horizontal interface between the lower layer and the upper layer. Spanwise and vertical velocities at the horizontal interface revealed the existence of horizontal vortices near the junction of the main channel and the floodplain where momentum exchange takes place. Further, the model result, showing the spanwise shear stresses distribution at the interface of symmetric and asymmetric compound channel, revealed the existence of peak shear stress near the channel junction. Sensitivity of the two important model parameters is also undertaken and their roles in longitudinal velocity distribution along the channel width are discussed.

show abstract

“…2.4, which shows macrovortices in the transition regions and a mean flow velocity distribution along the transversal direction (see Stocchino et al 2011). Recent experimental investigations (Stocchino and Brocchini 2010), which were based on use of the PIV technique, revealed that the population and properties of macrovortices largely depend on the typical depth gradients, i.e., on the ratio r h between the largest and smallest flow depths.…”

Section: Turbulence Evolving On the Horizontal Planementioning

confidence: 95%

“…The mixing induced by these dynamical domains can be described in terms of both absolute (single-particle) and relative (e.g., particle pairs) statistics (e.g., Provenzale 1999;LaCasce 2008;Stocchino et al 2011). Typically, under shallow flow conditions, macrovortices strongly influence the growth in time of the total absolute dispersion after an initial ballistic regime after their formation, leading to a (a) (b) Fig.…”

Section: Turbulence Evolving On the Horizontal Planementioning

confidence: 99%

See 1 more Smart Citation

Turbulence in Rivers

Franca

Brocchini

2015

Rivers – Physical, Fluvial and Environmental Processes

Self Cite

View full text Add to dashboard Cite

The study of turbulence has always been a challenge for scientists working on geophysical flows. Turbulent flows are common in nature and have an important role in geophysical disciplines such as river morphology, landscape modeling, atmospheric dynamics and ocean currents. At present, new measurement and observation techniques suitable for fieldwork can be combined with laboratory and theoretical work to advance the understanding of river processes. Nevertheless, despite more than a century of attempts to correctly formalize turbulent flows, much still remains to be done by researchers and engineers working in hydraulics and fluid mechanics. In this contribution we introduce a general framework for the analysis of river turbulence. We revisit some findings and theoretical frameworks and provide a critical analysis of where the study of turbulence is important and how to include detailed information of this in the analysis of fluvial processes. We also provide a perspective of some general aspects that are essential for researchers/ practitioners addressing the subject for the first time. Furthermore, we show some results of interest to scientists and engineers working on river flows.

show abstract

Lagrangian mixing in straight compound channels

Cited by 25 publications

References 31 publications

Transversal and longitudinal mixing in compound channels

Transversal and longitudinal mixing in compound channels

Development of Two-layered model for compound open-channel flow

Turbulence in Rivers

Contact Info

Product

Resources

About