scholarly journals Experimental Study of Flow Characteristics in A Rectangular Gravel Bed Channel

2021 ◽  
Vol 873 (1) ◽  
pp. 012047
Author(s):  
Robby Yussac Tallar ◽  
Dea Teodora Ferninda ◽  
Efferiki ◽  
Prabu Mandvi Hafiz Anjar Suhendar ◽  
Frankie Pandapotan Purba
Keyword(s):  
Experimental Study ◽  
Flow Velocity ◽  
Friction Factor ◽  
Flow Resistance ◽  
Open Channel ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Flume Experiments ◽  
Sediment Bed ◽  
Set Up

Abstract In an open channel flow, the characteristics of flow resistance are greatly affected by the roughness of the base and the walls of the channel. The existence of an object or other material, including gravel, also influenced the resistance of flow, therefore the purpose of this study is to examine the flow characteristics (flow velocity and flow resistance) in gravel open channel by using experimental study. A laboratory study to explore the effect of channel bed in terms of roughness of types of sediment on the hydraulics flow in 8 m length x 40 cm width a rectangular channel is presented. The study consists of an extensive set of rectangular flume experiments for flows with certain slope and sediment bed. The study was using the Before After Control Impact (BACI) method by set up five different scenarios. The results show that the lowest flow velocity (v=0.3041 m/sec) was occurred in the scenario 3 (50%sand and 50% gravel). Based on the Manning’ coefficient (n), it was also found that at the 100% discharge flow condition, the highest value of friction factor (f=0.0780) within 5 scenarios was scenario 3 with the sediment consisted of 50%sand and 50%gravel. Whereas the value of the lowest friction factor(f=0.0652) was scenario 1 with the sediment only gravel within. It concluded that the results gave the lower value of Manning’ coefficient (n) compared to the table of Manning’s coefficient (f= 0.04) for the channel with gravel base condition.

Flow Resistance Characteristics of a Specific Fuel RP-3 in Helical Tubes at Supercritical Pressure With Uniform Heat Flux

2017 ◽  
Author(s):  
Nan Zhang ◽  
Yanchen Fu ◽  
Haoran Huang ◽  
Jie Wen ◽  
Nigeer Te
Keyword(s):  
Heat Flux ◽  
Friction Factor ◽  
Mass Flux ◽  
Flow Resistance ◽  
Flow Characteristics ◽  
Supercritical Pressure ◽  
Uniform Heat Flux ◽  
Inlet Temperature ◽  
Uniform Heat ◽  
Helical Tubes

The flow resistance characteristics of aviation kerosene RP-3 in horizontal helical tubes at the supercritical pressure under heating condition are investigated. Both pressure drop and friction factor were examined under uniform heat flux of 50kW/m2−300kW/m2, mass flux from 786kg/m2s to 1375kg/m2s, and helical diameter from 20mm to 40mm. The influence of viscous factors on the resistance is analyzed to explore flow characteristics in a helical tube and provide a reference for the design of heat exchangers. Friction factor decreases with the increase of heat flux at low inlet temperatures 323K and 423K. It is explained that the viscosity changes more dramatically than the density. When the fluid inlet temperature is 523K and the fluid mean temperature Tb is close to pseudo-critical temperature, frictional flow resistance becomes significantly larger Tpc due to huge variations in thermal properties in the radical direction. The effect of centrifugal force makes the friction factor decline slowly. The friction factor goes up with the enlargement of mass flux when Tb>0.81Tpc. This phenomenon is caused by the larger radial velocity gradient under the large mass flux. Different helical diameters play the leading roles for the bending flow in the tubes.

scholarly journals 2D Numerical Study of Heat Transfer Enhancement Using Fish-Tail Locomotion Vortex Generators

2021 ◽  
Vol 8 (3) ◽  
pp. 386-392
Author(s):  
Ahmed Hashim Yousif ◽  
Hakim T. Kadhim ◽  
Kadhim K. Idan Al-Chlaihawi
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Number Range ◽  
Maximum Value ◽  
Fluid Flow Characteristics

In this paper, a numerical simulation is performed to study the effect of two types of concave vortex generators (VGs), arranged as fish-tail locomotion in a rectangular channel. The heat transfer and fluid flow characteristics with and without VGs are examined over the Reynolds number range 200≤Re≤2200.The two proposed types of the VGs are selected based on the speed of the fish movement which is arranged in different distances between them (d/H=0.6, 1, 1.3). The results show that the use of VGs can significantly enhance the heat transfer rate, but also increases the friction factor. The heat transfer performance is enhanced by (4-21.1%) reaching the maximum value by using the first type of the VGs at (d/H=1.3) due to better mixing of secondary flow and the new arrangement of the VGs which lead to decreasing the friction factor with an easy flow of fluid.

scholarly journals Experimental Study on Flow Characteristics in a Compound Open Channel with Flexible Vegetation

2021 ◽  
Vol 697 (1) ◽  
pp. 012013
Author(s):  
Xiaoxiao Guo ◽  
Hefang Jing ◽  
Weihong Wang ◽  
Juntao Wu ◽  
Qiaoling Zhang
Keyword(s):  
Experimental Study ◽  
Open Channel ◽  
Flow Characteristics ◽  
Flexible Vegetation

scholarly journals Experimental investigation of low-angle dune morphodynamics

2018 ◽  
Vol 40 ◽  
pp. 02056 ◽  
Author(s):  
Suleyman Naqshband ◽  
Bas Wullems ◽  
Timo de Ruijsscher ◽  
Ton Hoitink
Keyword(s):  
Experimental Study ◽  
Flow Resistance ◽  
Water Levels ◽  
Light Weight ◽  
Laboratory Setting ◽  
Central Importance ◽  
Flume Experiments ◽  
Upper Stage ◽  
Turbulence Production ◽  
Dune Height

Dunes commonly dominate the bed of sandy rivers and they are of central importance in predicting flow resistance and water levels. In the present study, we show that by using light-weight polystyrene particles as substrate in a laboratory setting, promising morphodynamic similarity is obtained between dunes in shallow flow (flume) and deep flow (field) conditions. In particular, results from our flume experiments show that dune lee-side angles, which are crucial in turbulence production and energy dissipation, better approximate dune lee-side angles observed in natural channels. Furthermore, dune height evolution towards upper stage plane bed observed in the present experimental study, closely follows dune height evolution as observed in world’s large rivers.

scholarly journals Experimental study of open-channel flow with partial double-layered vegetation

2019 ◽  
Vol 81 ◽  
pp. 01010 ◽  
Author(s):  
Xiaonan Tang ◽  
Hamidrez Rahimi ◽  
Prateek Singh ◽  
Zishun Wei ◽  
Yuxuan Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Riparian Vegetation ◽  
Open Channel ◽  
Open Channel Flow ◽  
Doppler Velocimetry ◽  
Flume Experiments ◽  
Flow Process ◽  
River Flood ◽  
Acoustic Doppler Velocimetry ◽  
Natural Rivers

Many rivers and wetlands have vegetation. The effect of riparian vegetation on ecological and flow process in channels has become increasingly important in river flood risk and aquatic environmental management. Most previous studies have been done on the flow structure of vegetation of the same height which is not realistic in natural rivers. There are only a few studies on flows with a mixing array of short and tall vegetation under either submerged or emergent flow condition. This paper is to undertake a novel experimental study on a flow with double-layered vegetation under submerged and emergent conditions, which often occur in most rivers. Two different heights of dowels, 10 cm and 20 cm, were used in the water flume to represent the short and tall vegetation respectively, and they were allocated on one side of the flume. Experiments in two flow depths were undertaken to represent different submergence ratios of vegetation, and velocities at various locations were measured by Acoustic Doppler Velocimetry (ADV) and propeller velocimetry. Experimental results show that the velocity profile is almost uniform within the depth of short vegetation in different configurations. The velocity starts to increase in the region near the edge of short vegetation, and then followed by a rapid increase through the height of tall vegetation to the free surface. Meanwhile, a strange shear layer exists laterally between vegetation and non-vegetation, showing that the vegetation significantly reduces the velocity of flow.

scholarly journals Experimental Study on the Flow Characteristics of a Gradually Expanding Open Channel Flow.

1996 ◽  
pp. 43-54
Author(s):  
Kouki Onitsuka ◽  
Masaru Ura ◽  
Juichiro Akiyama ◽  
Shin Sakamoto ◽  
Katsushi Seitoku
Keyword(s):  
Experimental Study ◽  
Channel Flow ◽  
Open Channel ◽  
Flow Characteristics ◽  
Open Channel Flow

scholarly journals Experimental analysis of the effect of bed-load movement on flow hydraulic characteristics

2021 ◽  
Author(s):  
Reza Estakhr ◽  
Ali Mahdavi Mazdeh ◽  
Mohammad Hossein Omid
Keyword(s):  
Friction Factor ◽  
Flow Resistance ◽  
Flow Characteristics ◽  
Shear Velocity ◽  
Bed Load ◽  
Mean Flow ◽  
Flow Friction ◽  
Rough Bed ◽  
Load Movement ◽  
Rough Beds

Abstract In this study, the effect of bed-load movement on mean flow characteristics was evaluated in two rigid rectangular flumes. The experiments consisted of creating flow conditions carrying sediments with mean diameters of D50 = 0.5, 0.6, and 2.84 mm over both smooth and rough beds. Various sediment concentrations were injected at the upstream end of the flume at non-deposit injection rates to study the effect of various concentrations on flow resistance. The effect of sediment movement on flow resistance was examined by comparing the results with those of clear water flows (without sediment injection on both smooth and rough beds). The results showed that the sediment transport in maximum injection rate may increase the friction factor up to 50 and 58 percent for smooth bed, and up to about 75 and 80 percent in rough bed with mean diameter of 0.5 and 0.6 mm. Besides, for D50 = 2.84 mm, the friction factor decreased in smooth bed and increased up to 50 percent in rough bed. In general, it can be concluded that bed-load transport can be increased by the flow friction factor. The results also showed that bed-loads may decrease the average velocity and increase shear velocity with extraction of momentum from the flow, which both of mentioned factors may increase the flow friction factor. Raising the bed-load concentration in the flow may increase the elevation of the friction factor, approaching a constant value after reaching to the aggregation threshold and generation of bed forms.

scholarly journals Rill flow resistance law under sediment transport

2021 ◽  
Author(s):  
Costanza Di Stefano ◽  
Alessio Nicosia ◽  
Vincenzo Palmeri ◽  
Vincenzo Pampalone ◽  
Vito Ferro
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Friction Factor ◽  
Flow Resistance ◽  
Fixed Bed ◽  
Accurate Estimate ◽  
Mean Flow ◽  
Mobile Bed ◽  
Resistance Equation ◽  
Rill Flow

Abstract Purpose In this paper, a deduced flow resistance equation for open-channel flow was tested using measurements carried out in mobile bed rills with sediment-laden flows and fixed bed rills. The main aims were to (i) assess the effect of sediment transport on rill flow resistance, and (ii) test the slope-flow velocity relationship in fixed bed rills. Methods The following analysis was developed: (i) a relationship between the Γ function of the velocity profile, the rill slope and the Froude number was calibrated using measurements carried out on fixed bed rills; (ii) the component of Darcy-Weisbach friction factor due to sediment transport was deduced using the corresponding measurements carried out on mobile bed rills (grain resistance and sediment transport) and the values estimated by flow resistance equation (grain resistance) for fixed bed rills in the same slope and hydraulic conditions; (iii) the Γ function relationship was calibrated using measurements carried out on mobile bed rills and the data of Jiang et al. (2018). Results This analysis demonstrated that the effect of sediment transport on rill flow resistance law is appreciable only for 7.7% of the examined cases and that the theoretical approach allows for an accurate estimate of the Darcy-Weisbach friction factor. Furthermore, for both fixed and mobile beds, the mean flow velocity was independent of channel slope, as suggested by Govers (1992) for mobile bed rills. Conclusions The investigation highlighted that the effect of sediment transport on rill flow resistance is almost negligible for most of the cases and that the experimental procedure for fixing rills caused the unexpected slope independence of flow velocity.

Sign in / Sign up

Export Citation Format

Share Document