Effects of a fully submerged boulder within a boulder array on the mean and turbulent flow fields: Implications to bedload transport

Papanicolaou, A. N.; Kramer, C. M.; Tsakiris, Achilleas G.; Stoesser, Thorsten; Bomminayuni, Sandeep Kumar; Chen, Zhuo

doi:10.2478/s11600-012-0044-6

Cited by 84 publications

(104 citation statements)

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“…The fluid solver is based on the LES code Hydro3D, a finite-difference-based Cartesian grid solver that has undergone Calculation of fluid-structure interaction: methods, refinements, applications Kara, Stoesser and McSherry excessive validation for different flows (e.g. Bomminayuni and Stoesser, 2009;Kara et al, 2012a;Kim and Stoesser, 2011;Kim et al, 2013;Papanicolaou et al, 2012). The code uses the diffuse direct forcing approach of Uhlmann (2005a), in which forces between Lagrangian marker points, representing the immersed body, and Eulerian (fluid) grid points are transferred by a discrete delta function.…”

Section: Fluid Solvermentioning

confidence: 99%

Calculation of fluid–structure interaction: methods, refinements, applications

Kara¹,

McSherry²,

Stoesser³

2015

Proceedings of the Institution of Civil Engineers - Engineering

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Section: Fluid Solvermentioning

confidence: 99%

Calculation of fluid–structure interaction: methods, refinements, applications

Kara¹,

McSherry²,

Stoesser³

2015

Proceedings of the Institution of Civil Engineers - Engineering

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“…In a previous study, Papanicolaou et al (2012) investigated the mean and turbulent flow fields in the vicinity of a fully submerged, spherical boulder within a boulder array mounted atop a flat rough porous flume bed. Through a systematic comparison of time-averaged, streamwise velocity profiles acquired around the boulder using an Acoustic Doppler Velocimeter (ADV), Papanicolaou et al (2012) provided an improved methodology for estimating u * using the boundary characteristics method (BCM) introduced by Afzalimehr and Anctil (2000).…”

Section: Time-averaged and Turbulent Flow Fieldsmentioning

confidence: 99%

“…Through a systematic comparison of time-averaged, streamwise velocity profiles acquired around the boulder using an Acoustic Doppler Velocimeter (ADV), Papanicolaou et al (2012) provided an improved methodology for estimating u * using the boundary characteristics method (BCM) introduced by Afzalimehr and Anctil (2000). The calculated u * by the BCM was in turn combined with the velocity defect law parameterization (e.g., Kironoto and Graf 1994;Ferro 2003) to derive a self-similar timeaveraged, streamwise velocity profile for the flow field around the boulder.…”

Section: Time-averaged and Turbulent Flow Fieldsmentioning

confidence: 99%

“…(2) scenario 2, which was the experimental run reported in Papanicolaou et al (2012). Hence, scenario 2 involved an array of 48 identical, fully submerged boulders (d c = 55 mm) placed in a staggered arrangement atop the rough bed within the test section.…”

Section: Time-averaged and Turbulent Flow Fieldsmentioning

confidence: 99%

“…To enable quantitative comparisons between scenarios 1 and 2, the approach flow conditions in the experiment performed for scenario 1, as described in detail in the following Subsections 2.2., 2.3 and 2.4, were identical to the approach flow conditions for the experiment reported by Papanicolaou et al (2012). Only the pertinent details from the experimental procedure of the Papanicolaou et al (2012) study are re-iterated here. The reader is referred to their study for a comprehensive presentation of the experimental conditions.…”

Section: Time-averaged and Turbulent Flow Fieldsmentioning

confidence: 99%

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Influence of collective boulder array on the surrounding time-averaged and turbulent flow fields

et al. 2014

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Arrays of large immobile boulders, which are often encountered in steep mountain streams, affect the timing and magnitude of sediment transport events through their interactions with the approach flow. Despite their importance in the quantification of the bedload rate, the collective influence of a boulder array on the approach timeaveraged and turbulent flow field has to date been overlooked. The overarching objective is, thus, to assess the collective effects of a boulder array on the time-averaged and turbulent flow fields surrounding an individual boulder within the array, placing particular emphasis on highlighting the bed shear stress spatial variability. The objective of this study is pursued by resolving and comparing the timeaveraged and turbulent flow fields developing around a boulder, with and without an array of isolated boulders being present. The results show that the effects of an individual boulder on the time-averaged streamwise velocity and turbulence intensity were limited to the boulder's immediate vicinity in the streamwise (x/dc < 2-3) and vertical (z/dc < 1) directions. Outside of the boulder's immediate vicinity, the time-averaged streamwise velocity was found to be globally decelerated. This global deceleration was attributed to the form drag generated collectively by the boulder array. More importantly, the boulder array reduced the applied shear stress exerted on the individual boulders found within the array, by absorbing a portion of the total applied shear. Furthermore, the array was found to have a "homogenizing" effect on the near-bed turbulence thus significantly reducing the turbulence intensity in the near-bed region. The findings of this study suggest that the collective boulder array bears a portion of the total applied bed shear stress as form drag, hence reducing the available bed shear stress for transporting incoming mobile sediment. Thus, the effects of the boulder array should not be ignored in sediment transport predictions. These effects are encapsulated in this study by Equation (6). Citation: Tsakiris AG, Papanicolaou AN , Hajimirzaie SM, et al. (2014) Influence of collective boulder array on the surrounding time-averaged and turbulent flow fields. Journal of Mountain Science 11(6).

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Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition

Ortiz

Ashton

Nepf

2013

J. Geophys. Res. Earth Surf.

117

125

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[1] The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the spatial distribution of flow is connected to the spatial distribution of suspended sediment deposition. Patches of rigid, emergent, and flexible, submerged vegetation were considered, with two different stem densities. For the rigid emergent vegetation, flow adjustment was primarily two-dimensional, with flow deflected in the horizontal plane. Horizontal shear layers produced a von Kármán vortex street. Flow through the patch shifted the vortex street downstream, resulting in a region directly downstream of the patch in which both the mean and turbulent velocities were diminished. Net deposition was enhanced within this region. In contrast, for the flexible, submerged vegetation, flow adjustment was three-dimensional, with shear layers formed in the vertical and horizontal planes. Because of strong vertical circulation, turbulent kinetic energy was elevated directly downstream of the patch. Consistent with this, deposition was not enhanced at any point in the wake. This comparison suggests that morphological feedbacks differ between submerged and emergent vegetation.

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Effects of a fully submerged boulder within a boulder array on the mean and turbulent flow fields: Implications to bedload transport

Cited by 84 publications

References 50 publications

Calculation of fluid–structure interaction: methods, refinements, applications

Calculation of fluid–structure interaction: methods, refinements, applications

Influence of collective boulder array on the surrounding time-averaged and turbulent flow fields

Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition

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