Fluids

Editorial

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2 pages, 168 KiB

Open AccessEditorial

Environmental Hydraulics, Turbulence and Sediment Transport

by Jaan H. Pu

Fluids 2022, 7(2), 48; https://doi.org/10.3390/fluids7020048 - 23 Jan 2022

Cited by 1 | Viewed by 1836

Abstract

Within the environmental flows, i [...] Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

Research

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15 pages, 3634 KiB

Open AccessArticle

Self-Preservation of Turbulence Statistics in the Wall-Wake Flow of a Bed-Mounted Horizontal Pipe

by Kalpana Devi, Prashanth Reddy Hanmaiahgari, Ram Balachandar and Jaan H. Pu

Fluids 2021, 6(12), 453; https://doi.org/10.3390/fluids6120453 - 14 Dec 2021

Cited by 5 | Viewed by 2214

Abstract

This research article analyzed the self-preserving behaviour of wall-wake region of a circular pipe mounted horizontally over a flat rigid sand bed in a shallow flow in terms of mean velocity, RSS, and turbulence intensities. The study aims to investigate self-preservation using appropriate [...] Read more.

This research article analyzed the self-preserving behaviour of wall-wake region of a circular pipe mounted horizontally over a flat rigid sand bed in a shallow flow in terms of mean velocity, RSS, and turbulence intensities. The study aims to investigate self-preservation using appropriate length and velocity scales.in addition to that wall-normal distributions of the third-order correlations along the streamwise direction in the wake region are analyzed. An ADV probe was used to record the three-dimensional instantaneous velocities for four different hydraulic and physical conditions corresponding to four cylinder Reynolds numbers. The results revealed that the streamwise velocity deficits, RSS deficits, and turbulence intensities deficits distributions displayed good collapse on a narrow band when they were non-dimensionalized by their respective maximum deficits. The wall-normal distance was non-dimensionalized by the half velocity profile width for velocity distributions, while the half RSS profile width was used in the case of the RSS deficits and turbulence intensities deficits distributions. The results indicate the self-preserving nature of streamwise velocity, RSS, and turbulence intensities in the wall-wake region of the pipe. The third-order correlations distributions indicate that sweep is the dominant bursting event in the near-bed zone. At the same time, ejection is the dominant bursting event in the region above the cylinder height. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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16 pages, 6281 KiB

Open AccessArticle

Stability and Consolidation of Sediment Tailings Incorporating Unsaturated Soil Mechanics

by Alfrendo Satyanaga, Martin Wijaya, Qian Zhai, Sung-Woo Moon, Jaan Pu and Jong R. Kim

Fluids 2021, 6(12), 423; https://doi.org/10.3390/fluids6120423 - 24 Nov 2021

Cited by 14 | Viewed by 3032

Abstract

Tailing dams are commonly used to safely store tailings without damaging the environment. Sand tailings (also called Sediment tailings) usually have a high water content and hence undergo consolidation during their placement. As the sediment tailings are usually placed above the ground water [...] Read more.

Tailing dams are commonly used to safely store tailings without damaging the environment. Sand tailings (also called Sediment tailings) usually have a high water content and hence undergo consolidation during their placement. As the sediment tailings are usually placed above the ground water level, the degree of saturation and permeability of the sediment tailing is associated with the unsaturated condition due to the presence of negative pore-water pressure or suction. Current practices normally focus on the analyses saturated conditions. However, this consolidation process requires the flow of water between saturated and unsaturated zones to be considered. The objective of this study is to investigate the stability and consolidation of sediment tailings for the construction of road pillars considering the water flow between saturated and unsaturated zones. The scope of this study includes the unsaturated laboratory testing of sediments and numerical analyses of the road pillar. The results show that the analyses based on saturated conditions overestimate the time required to achieve a 90% degree of consolidation. The incorporation of the unsaturated soil properties is able to optimize the design of slopes for road pillars into steeper slope angles. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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15 pages, 9135 KiB

Open AccessArticle

Toward a Better Understanding of Sediment Dynamics as a Basis for Maintenance Dredging in Nagan Raya Port, Indonesia

by Muhammad Zikra, Shaskya Salsabila and Kriyo Sambodho

Fluids 2021, 6(11), 397; https://doi.org/10.3390/fluids6110397 - 3 Nov 2021

Cited by 6 | Viewed by 1723

Abstract

The Port of 2 × 110 MW Nagan Raya Coal Fired Steam Power Plant is one of the facilities constructed by the State Electricity Company in Aceh Province, Indonesia. During its operation, which began in 2013, the port has dealt with large amounts [...] Read more.

The Port of 2 × 110 MW Nagan Raya Coal Fired Steam Power Plant is one of the facilities constructed by the State Electricity Company in Aceh Province, Indonesia. During its operation, which began in 2013, the port has dealt with large amounts of sedimentation within the port and ship entrances. The goal of this study is to mitigate the sedimentation problem in the Nagan Raya port by evaluating the effect of maintenance dredging. Field measurements, and hydrodynamic and sediment transport modeling analysis, were conducted during this study. Evaluation of the wind data showed that the dominant wind direction is from south to west. Based on the analysis of the wave data, the dominant wave direction is from the south to the west. Therefore, the wave-induced currents in the surf zone were from south to north. Based on the analysis of longshore sediment transport, the supply of sediments to Nagan Raya port was estimated to be around 40,000–60,000 m³ per year. Results from the sediment model showed that sedimentation of up to 1 m was captured in areas of the inlet channel of Nagan Raya port. The use of a passing system for sand is one of the sedimentation management solutions proposed in this study. The dredged sediment material around the navigation channel was dumped in a dumping area in the middle of the sea at a depth of 11 m, with a distance of 1.5 km from the shoreline. To obtain a greater maximum result, the material disposal distance should be dumped further away, at least at a depth of 20 m or a distance of 20 miles from the coastline. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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21 pages, 1968 KiB

Open AccessArticle

Experimental Characterization of the Flow Field around Oblong Bridge Piers

by Ana Margarida Bento, Teresa Viseu, João Pedro Pêgo and Lúcia Couto

Fluids 2021, 6(11), 370; https://doi.org/10.3390/fluids6110370 - 20 Oct 2021

Cited by 10 | Viewed by 2224

Abstract

The prediction of scour evolution at bridge foundations is of utmost importance for engineering design and infrastructures’ safety. The complexity of the scouring inherent flow field is the result of separation and generation of multiple vortices and further magnified due to the dynamic [...] Read more.

The prediction of scour evolution at bridge foundations is of utmost importance for engineering design and infrastructures’ safety. The complexity of the scouring inherent flow field is the result of separation and generation of multiple vortices and further magnified due to the dynamic interaction between the flow and the movable bed throughout the development of a scour hole. In experimental environments, the current approaches for scour characterization rely mainly on measurements of the evolution of movable beds rather than on flow field characterization. This paper investigates the turbulent flow field around oblong bridge pier models in a well-controlled laboratory environment, for understanding the mechanisms of flow responsible for current-induced scour. This study was based on an experimental campaign planned for velocity measurements of the flow around oblong bridge pier models, of different widths, carried out in a large-scale tilting flume. Measurements of stream-wise, cross-wise and vertical velocity distributions, as well as of the Reynolds shear stresses, were performed at both the flat and eroded bed stages of scouring development with a high-resolution acoustic velocimeter. The time-averaged values of velocity and shear stress are larger in the presence of a developed scour hole than in the corresponding flat bed configuration. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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15 pages, 2471 KiB

Open AccessArticle

The Hydrodynamic Moment of a Floating Structure in Finite Flowing Water

by Zhen Cui, Shi-Yang Pan and Yue-Jun Chen

Fluids 2021, 6(9), 307; https://doi.org/10.3390/fluids6090307 - 31 Aug 2021

Cited by 1 | Viewed by 2297

Abstract

The implementation of floating structures has increased with the construction of new sluices for flood control, and the hydrodynamic moment of a floating structure affects the safety and operation of that structure. Based on basic hydrodynamic theory, theoretical analysis and 121 physical model [...] Read more.

The implementation of floating structures has increased with the construction of new sluices for flood control, and the hydrodynamic moment of a floating structure affects the safety and operation of that structure. Based on basic hydrodynamic theory, theoretical analysis and 121 physical model tests were conducted to study the relationships between the hydrodynamic moment and the influencing factors of floating structures, namely, the shape parameter, hydraulic conditions, and draft depth. Stepwise regression fitting based on the least squares method was performed to obtain a mathematical expression of the hydrodynamic moment, and the experimental results show that hydrodynamic factors significantly influence the hydrodynamic moment of such structures. The results predicted by the mathematical expression agree with the experimental results, and thus, the proposed expression can be used to comprehensively analyze and study the safety of a floating structure under the action of flow in finite water. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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14 pages, 3215 KiB

Open AccessArticle

A Comparative Study between Sand- and Gravel-Bed Open Channel Flows in the Wake Region of a Bed-Mounted Horizontal Cylinder

by Kalpana Devi, Prashanth Reddy Hanmaiahgari, Ram Balachandar and Jaan H. Pu

Fluids 2021, 6(7), 239; https://doi.org/10.3390/fluids6070239 - 1 Jul 2021

Cited by 6 | Viewed by 2632

Abstract

In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart [...] Read more.

In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake region of a horizontal bed-mounted cylinder over the sand-bed with that over the gravel-bed. Three experimental runs, two for the sand-bed and one for the gravel-bed with similar physical and hydraulic conditions, were recorded to fulfil this purpose. The Acoustic Doppler Velocimetry (ADV) probe was used for measuring the three-dimensional (3D) instantaneous velocity data. This comparative study shows that the magnitude of mean streamwise flow velocity, streamwise Reynolds normal stress, and Reynolds shear stress are reduced on the gravel-bed compared to the sand-bed. Conversely, the vertical velocities and vertical Reynolds normal stress are higher on the gravel-bed than the sand-bed. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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Review

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16 pages, 2330 KiB

Open AccessReview

Review of Suspended Sediment Transport Mathematical Modelling Studies

by Joseph T. Wallwork, Jaan H. Pu, Snehasis Kundu, Prashanth R. Hanmaiahgari, Manish Pandey, Alfrendo Satyanaga, Md. Amir Khan and Alastair Wood

Fluids 2022, 7(1), 23; https://doi.org/10.3390/fluids7010023 - 3 Jan 2022

Cited by 8 | Viewed by 3586

Abstract

This paper reviews existing studies relating to the assessment of sediment concentration profiles within various flow conditions due to their importance in representing pollutant propagation. The effects of sediment particle size, flow depth, and velocity were considered, as well as the eddy viscosity [...] Read more.

This paper reviews existing studies relating to the assessment of sediment concentration profiles within various flow conditions due to their importance in representing pollutant propagation. The effects of sediment particle size, flow depth, and velocity were considered, as well as the eddy viscosity and Rouse number influence on the drag of the particle. It is also widely considered that there is a minimum threshold velocity required to increase sediment concentration within a flow above the washload. The bursting effect has also been investigated within this review, in which it presents the mechanism for sediment to be entrained within the flow at low average velocities. A review of the existing state-of-the-art literature has shown there are many variables to consider, i.e., particle density, flow velocity, and turbulence, when assessing the suspended sediment characteristics within flow; this outcome further evidences the complexity of suspended sediment transport modelling. Full article

(This article belongs to the Special Issue Environmental Hydraulics, Turbulence and Sediment Transport)

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