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Sruthi Thazhathe Kalathil

Bio: Sruthi Thazhathe Kalathil is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Turbulence & Turbulence kinetic energy. The author has an hindex of 2, co-authored 4 publications receiving 9 citations.

Papers
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Journal ArticleDOI
24 Jun 2019
TL;DR: In this paper, steppools are one of the major types of bed morphology prevalent in mountain streams and they have a unique flow structure as compared to low-gradient streams, in terms of large boundary elements and...
Abstract: Step-pools are one of the major types of bed morphology prevalent in mountain streams. They have a unique flow structure as compared to low-gradient streams, in terms of large boundary elements and...

9 citations

Journal ArticleDOI
TL;DR: In this paper, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°.
Abstract: Intake canals are used to withdraw water from rivers for various purposes. Sedimentation in the intake canal reduces the quality and quantity of water being delivered. In this study, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°. The variables in the study included vane angle, number of vane rows, and vane spacing in terms of mean flow depth in the main channel. In addition to the commonly used vane array with uniform vane heights, three other vane-height configurations were also tested. The least local scour around vanes and highest sediment reduction (~70%) were observed for vanes oriented at a 15° vane angle with an increasing vane-height configuration placed in two rows. It was also observed that control of sediment entry into the intake canal increased with an increase of both vane spacing and number of vane rows.

7 citations

Journal ArticleDOI
TL;DR: In this paper, a regression equation of the form Power-Allometric1 has been proposed to relate the normalized turbulent kinetic energy with the velocity magnitude, and the range of Reynolds shear stress and energy dissipation factor existent in the step-pool systems.
Abstract: The morphology of step-pools is often implemented for ecological restoration and for the creation of close-to-nature fish passes. Step-pools display spatio-temporal variations in bed and flow characteristics due to meso-scale units such as step, tread, base of step, and pool. Exclusive research on the effects of bed variations in step-pools on the flow dynamics is limited. Here, we conducted laboratory experiments on a physical model downscaled from a field site in the Western Ghats, Kerala, India. The results of Kruskal–Wallis ANOVA show significant differences in the velocity and turbulent intensities for the morphological units. A regression equation of the form Power-Allometric1 has been proposed to relate the normalized turbulent kinetic energy with the velocity magnitude. The present study also estimated the range of Reynolds shear stress and energy dissipation factor existent in the step-pool systems. The normalized values of Reynolds shear stress in the x–z plane ranged from − 19.477 to 13.729, and energy dissipation factors obtained for the three step-pool systems are 321, 207, and 123 W/m3; both the results reveal insufficient pool volume for adequate energy dissipation. The study concludes that while designing close-to-nature step-pool fish passes, pool dimensions should be finalized with respect to the target aquatic species.

1 citations

Journal ArticleDOI
TL;DR: In this paper , the authors developed design charts and rating curves based on numerical modeling using the computational fluid dynamics software FLOW-3D® HYDRO for step-pool nature-like fishways.
Abstract: Hydraulic considerations specific for the design of step-pool nature-like fishways (NLFs) are limited to the body dimensions of the target species. Additional hydraulic criteria for flow depth, maximum values for each of pool depth, velocity, and turbulent kinetic energy in terms of the weir opening width and discharge can help design an optimum step-pool NLF. The present study developed design charts and rating curves based on numerical modeling using the computational fluid dynamics software FLOW-3D® HYDRO. Instantaneous velocity measurements on a 1:4 scaled physical model of a step-pool nature-like fishway designed as per the available design guidelines have been used to validate the numerical model. The hydrodynamics of the fishway with respect to the weir opening ratio b r (0.10, 0.25, 0.45, 0.65, and 1.00) and discharge Q (0.1–1.5 m3/s) was analyzed through numerical simulations on a prototype scale. The simulation results showed that the maximum flow velocity and the averaged velocity over the crest at b r = 0.10 and 0.25 are considerably lower than at b r > 0.25. The maximum turbulent kinetic energy and energy dissipation factors for the tested range of discharges were within recommended limits for b r = 0.10 and 0.25. The present study outcome in terms of the design charts and rating curves that illustrate the relationship between different variables can be used for an optimum design and ease in field implementation. In addition, the bed structure of the step-pool NLF presented in this study can be used to recreate full-scale or pilot models.
Book ChapterDOI
01 Jan 2021
TL;DR: In this paper, collars have been introduced to submerged vanes to test its performance in the reduction of both sediment entry and local scour around vanes, and it was found that 40° is the optimum vane angle for maximum reduction in sediment entry into the intake canal.
Abstract: Intake canals transport water and sediments from main rivers to power plants, irrigation fields, and for various other purposes. Increased sediment load in the intake canal leads to reduction in the quality and quantity of water. Submerged vanes are installed at the entrance of intake canals to counteract the secondary circulation and reduce the sediment entry into the intake canals. In the present study, collars have been introduced to submerged vanes to test its performance in the reduction of both sediment entry and local scour around vanes. The vane angles tested are 15°, 35°, 40° and 45°. The ratio of vane spacing to vane height is 5 and the two collar diameters considered are three and four times the vane height, respectively. It is found that 40° is the optimum vane angle for maximum reduction in sediment entry into the intake canal of 85.36%. Collars reduced the local scour and sediment entry (%) by a maximum of 69.08% and 24.84%, respectively, for a 15° vane angle. However, introduction of collar reduced the performance for vane angles 35°, 40°, and 45° in controlling sediment entry into the intake canal.

Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors review progress on five key questions related to how boulders influence the evolution of unglaciated, eroding landscapes: 1) What factors control boulder production on eroding hillslopes and the subsequent downslope evolution of the boulder size distribution.

27 citations

Journal Article
TL;DR: In this paper, an experiment was conducted to study the maximum flow resistance of step pool streams and the morphology of the steps formed from clastic materials, and the step pool formation was qualitatively simulated to analyze numerically the formation process.
Abstract: An experiment was conducted to study the maximum flow resistance of step pool streams and the morphology of the steps formed from clastic materials. The step pool formation was qualitatively simulated to analyze numerically the formation process. A flume 4.88 mm long and .15 m wide was used and flow velocity measurements were done by electronically timing passage of salt plume down the flume. Observations showed that the natural step pool streams arranged the morphology to maximize flow resistance.

9 citations

Journal ArticleDOI
31 Dec 2020-Water
TL;DR: In this paper, three-dimensional numerical simulations were performed for different flow rates and various geometrical parameters of step-pools in steep open channels to gain insight into the occurrence of energy loss and its dependence on the flow structure.
Abstract: Three-dimensional numerical simulations were performed for different flow rates and various geometrical parameters of step-pools in steep open channels to gain insight into the occurrence of energy loss and its dependence on the flow structure. For a given channel with step-pools, energy loss varied only marginally with increasing flow rate in the nappe and transition flow regimes, while it increased in the skimming regime. Energy loss is positively correlated with the size of the recirculation zone, velocity in the recirculation zone and the vorticity. For the same flow rate, energy loss increased by 31.6% when the horizontal face inclination increased from 2° to 10°, while it decreased by 58.6% when the vertical face inclination increased from 40° to 70°. In a channel with several step-pools, cumulative energy loss is linearly related to the number of step-pools, for nappe and transition flows. However, it is a nonlinear function for skimming flows.

9 citations

Journal ArticleDOI
TL;DR: In this paper, a method for sediment control in damless water intake hydraulic units consisting in artificial transverse circulation (ATC) generated by redistributing specific water flow rates in the cross-section of the supply channel is described.
Abstract: Abstract Introduction. In this article, we describe a method for sediment control in damless water intake hydraulic units consisting in artificial transverse circulation (ATC) generated by redistributing specific water flow rates in the cross-section of the supply channel. One of the simplest and most effective anti-sediment elements working according to this principle is the submerged vane (SV). The intensity of the ATC formed in the flow depends on the flow regime and the planned-geometric characteristics of the vanes. Available recommendations on the selection of the rational characteristics of SV under the conditions of river damless water intake appear to be contradictory, thus requiring clarification. This study is aimed at examining the interaction between SV and a model flow without water trapping under various planned-geometric characteristics of the vane and experimental hydraulic regimes of its work using a physical model of the errosion-resistant channel. In addition, we set out to assess the effect of essential parameters on the intensity of the ATC generated in the flow. Materials and methods. This research was based on physical modelling hydraulic studies and theoretical calculations. Five hydraulic modes of vane operation with different planned-geometric characteristics were studied using a physical model of the erosion-resistant channel. Multiple regression analysis of the obtained experimental data was carried out. Results. The results of laboratory hydraulic studies on the SV operating conditions are presented. Experimental dependencies characterising the intensity of the ATC generated in the flow are plotted. A multiple regression equation is derived for the amount of the data obtained. Conclusions. It is established that the relative height of the vane and its angle to the side of the flume (coastline) has a significant effect on the intensity of the generated ATC. It is experimentally confirmed for the first time that SV shows little efficiency in high water horizons in terms of in-flow ATC generation.

3 citations

01 Jan 2000
TL;DR: In this article, the authors identify the flow conditions under which stable bedforms exist; provide the geometric characteristics of these bedforms; measure the magnitude of the streamwise velocity and energy dissipation factor; and determine the friction factor under various flow conditions and gravel sizes.
Abstract: The goal of this study was to identify the flow conditions under which stable bedforms exist; provide the geometric characteristics of these bedforms; measure the magnitude of the streamwise velocity and energy dissipation factor; and determine the friction factor under various flow conditions and gravel sizes. Design criteria and recommendations for stable bedforms were provided upon the termination of this research. Stable bedforms are defined as those bedforms of which the spatial characteristics (height and spacing) do not change with time. The focus of this study was on streams with slopes greater than 3%, as clear design requirements for bed geomorphologic stability are lacking for these cases, and they are of particular interest in the design and retrofit of culverts for both anadromous and resident migratory fish passage.

2 citations