To Investigate the Flow Structure of Discontinuous Vegetation Patches of Two Vertically Different Layers in an Open Channel

Anjum, Naveed; Ghani, Usman; Pasha, Ghufran Ahmed; Latif, Abid; Sultan, Tahir; Ali, Shahid

doi:10.3390/w10010075

Cited by 35 publications

(22 citation statements)

References 31 publications

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“…Different positions at 1 D upstream and downstream of the circular vegetation patch were selected to investigate the flow properties (as shown in Figure a,c). This type of experimental setup has also been used by many researchers upstream and downstream of individual vegetation elements (Anjum, Ghani, Pasha, Latif, et al, ; Liu, Diplas, Hodges, & Fairbanks, ) as well as at some distance directly before and after circular patches of vegetation (Meire et al, ; Shi, Jiang, & Nepf, ). A flow rate of 0.009 m 3 /s was adopted in all the experiments.…”

Section: Methodsmentioning

confidence: 99%

“…Zhang, Wang, Xu, and Dai () and Hirschowitz and James () studied the flow characteristics in a vegetated open channel with nonsubmerged condition. The turbulence characteristics behind rigid circular vegetation structures have been numerically investigated by Anjum et al (Anjum, Ghani, Pasha, Latif, et al, ; Anjum, Ghani, Pasha, Rashid, et al, ). In addition, Burke and Stolzenbach () and Neary () implemented numerical models to simulate velocity profiles of the flows in the presence of vegetation.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the turbulent flow characteristics in an open channel with staggered vegetation patches

Ghani

Anjum

Pasha

et al. 2019

River Research & Apps

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In the present study, flow around circular and staggered vegetation patches was investigated numerically. For turbulence modelling, the Reynolds-averaged Navier-Stokes technique and Reynolds stress model were adopted. The numerical model was validated with the experimental data using varying vegetation density and flow velocities. The simulated results of mean stream-wise velocities were in close agreement with the experimental results. The results show that the mean stream-wise velocity in the downstream regions of vegetation patches were reduced, whereas the velocity in the free stream regions were increased. The influence of neighbouring and staggered vegetation patches on the flow was observed. The vegetation patches with larger nondimensional flow blockage (aD = 2.3, where a is the frontal area per volume of patches, and D is the diameter of vegetation patches) offered more turbulence when compared to the patches with a smaller flow blockage (aD = 1.2). Larger turbulence in the form of kinetic energy and turbulent intensity was recorded within the vegetation as well as the regions directly behind the patches. Negative Reynolds stresses were observed at the top of submerged vegetation. The turbulence characteristics peaked at the top of vegetation, that is, z/h = 1.0 (where z is the flow depth, and h is the vegetation height), which may be migrated vertically as the frontal area of the vegetation patch is increased. This high frontal area also increased stream-wise velocity above the vegetation, leading to an increased variation in turbulence around the vegetation canopy.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the turbulent flow characteristics in an open channel with staggered vegetation patches

Ghani

Anjum

Pasha

et al. 2019

River Research & Apps

Self Cite

View full text Add to dashboard Cite

show abstract

“…In this study, the models were constructed in FLUENT 13.0 to analyze two-phase flow using the ANSYS solver [32]. The control equations consisted of continuity and momentum equations and particle component conservation equations of mass and momentum [33]. The continuity and momentum equations can be implemented using Reynolds' transport theorem, and by applying Newton's second law [34,35].…”

Section: Governing Equations and Mathematical Modelmentioning

confidence: 99%

Functional Relationship between Soil Slurry Transfer and Deposition in Urban Sewer Conduits

Yangho

Lee

2018

Water

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Soil slurry deposited on the surface of the Earth during rainfall mixes with fluids and flows into urban sewer conduits. Turbulent energy and energy dissipation in the conduits lead to separation, and sedimentation at the bottom lowers the discharge capacity of conduits. This study proposes a functional relationship between shear stress in urban sewer conduits and the physical properties of particles in a conduit bed containing less than 20 mm of soil. Several conditions were implemented for analyzing two-phase flow (soil slurry and fluid in urban sewer conduits) in terms of turbulent flow by considering soil slurry flowing into urban sewer conduits. The internal flows of fluid and soil slurry in urban sewer conduits were numerically analyzed and modeled by applying the Navier-Stokes equation and the k-ε turbulence model. The transfer deposition of the soil slurry in the conduits was reviewed and, based on the results, a limiting tractive force was calculated and used to propose criteria for transfer deposition occurring in urban sewer conduits.

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“…These methods may be costly for developing countries because of significant capital investment requirements [18]. Currently, ecological, natural methods are widely considered in many developed and underdeveloped countries [19][20][21][22][23]. Ecosystem degradation is a major cause of increasing water resources management challenges [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

Ahmed

Ghumman

2019

Water

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In this study, a series of laboratory experiments were conducted to investigate the energy loss through the hybrid defense system (HDS) in the order of dike, moat, and emergent vegetation in steady subcritical flow conditions. The results of HDS were compared with a single defense system (SDS) comprising only vegetation (OV). The dimensions of dike were kept constant while two different shapes (trapezoidal and rectangular) of moat were considered. The impacts of vegetation of variable thickness and density were investigated. Two combinations of HDS were investigated including the combination of dike and vegetation (DV) and the combination of dike, moat, and vegetation (DMV). The effect of backwater rise due to the vegetation, hydraulic jump formation and the impact of the arrival time of floodwater on energy dissipation were investigated. It was observed that on the upstream side of obstructions, the backwater depth increased by increasing the Froude number in both the SDS and HDS. The hydraulic jump observed in HDS was classified and the energy dissipation due to it was calculated. Under various conditions investigated in this paper, the maximum average energy dissipation was 32% in SDS and 46% in HDS. The trapezoidal moat performed better than rectangular moat as energy dissipater. The delay time was also greater with trapezoidal moat as compared to that in rectangular one. The maximum delay time was 140 s in the case of HDS. Hence, the hybrid defense system offered maximum resistance to the flow of water, thus causing a significant energy loss. For each case of SDS and HDS, empirical equations were developed by regression analysis to estimate the energy dissipation amounts.

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To Investigate the Flow Structure of Discontinuous Vegetation Patches of Two Vertically Different Layers in an Open Channel

Cited by 35 publications

References 31 publications

Investigating the turbulent flow characteristics in an open channel with staggered vegetation patches

Investigating the turbulent flow characteristics in an open channel with staggered vegetation patches

Functional Relationship between Soil Slurry Transfer and Deposition in Urban Sewer Conduits

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

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