scholarly journals The Effect of Confluence Angle on the Flow Pattern at a Rectangular Open-Channel

2014 ◽  
Vol 4 (1) ◽  
pp. 576-580
Author(s):  
F. Rooniyan
Keyword(s):  
Flow Pattern ◽  
Separation Zone ◽  
Morphological Changes ◽  
Flow Behavior ◽  
Main Channel ◽  
Flow Discharge ◽  
Urban Sewage ◽  
Discharge Ratio ◽  
Drainage Channels ◽  
Junction Geometry

Flow connection in channels is a phenomenon which frequently happens in rivers, water and drainage channels and urban sewage systems. The phenomenon appears to be more complex in rivers than in channels, especially at the y-junction bed joint that causes erosion and sedimentation at some areas resulting to morphological changes. Flow behavior at the channel junction area depends on variables such as channel geometry, discharge ratio, tributary width and y-junction connection angle of the channel, bed level changes at the bed joint, flow characteristic at the bed joint upstream and flow Froude number in different sections. In this research, fluent numerical model and junction angles of 30o, 45o & 60o are used to analyze and evaluate the effect of channel junction geometry on the flow pattern and the flow separation zone dimensions in different ratios of flow discharge (upstream channel discharge to total discharge of the flow). Results for two ratios of flow discharge are represented. Results are in agreement with earlier studies and it is shown that the change of the channel crossing angle affects the flow pattern in the main channel and also that the dimensions of the created separation zone in the main channel become larger when the crossing angle increases. This phenomenon can also be observed when the flow discharge ratio is lower. Analysis showed that the least dimension of the separation zone will be at the crossing angle of 45o .

scholarly journals Effect of a Submerged Vane-Field on the Flow Pattern of a Movable Bed Channel with a 90° Lateral Diversion

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 828
Author(s):  
Joana Baltazar ◽  
Elsa Alves ◽  
Gökçen Bombar ◽  
António Heleno Cardoso
Keyword(s):  
Flow Pattern ◽  
Water Discharge ◽  
Main Channel ◽  
Bed Load ◽  
Bed Morphology ◽  
Discharge Ratio ◽  
Submerged Vane ◽  
Diversion Channel ◽  
Movable Bed ◽  
Lateral Diversion

This laboratory study focused on the effect of a submerged vane-field on the flow pattern and bed morphology near and inside the entrance reach of a movable bed 90° lateral diversion. The system was modelled under live bed conditions for a water discharge ratio of ≈0.2. Two experiments were run until bed equilibrium was reached: with and without a vane-field installed close to the diversion entrance to control the transfer of sediments into the diversion channel. The equilibrium bed morphology and the associated 3D flow field were measured in great detail. The bed load diverted into the diversion was reduced by approximately one quarter due to the action of the vane-field. The vanes prevented the formation of the diversion vortex in the main channel, upstream of the diversion’s entrance, thus contributing to that decrease. They also created a main channel vortex that started at the most upstream vanes and further decreased the amount of bed load entering the diversion. The flow separation zone inside the diversion was larger with vanes, but conveyance was balanced through a slightly deeper scour trench therein. The flow structures described were confirmed through the measurements of the turbulent kinetic energy.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

scholarly journals Physical modelling of energy losses at surcharged three-way junction manholes in drainage system

2021 ◽  
Author(s):  
Q. Li ◽  
J. Xia ◽  
M. Zhou ◽  
S. Deng ◽  
H. Zhang ◽  
...  
Keyword(s):  
Energy Loss ◽  
Flow Structure ◽  
Water Depth ◽  
Drainage System ◽  
Physical Modelling ◽  
Head Loss ◽  
Geometrical Parameters ◽  
Flow Discharge ◽  
Discharge Ratio ◽  
Loss Coefficients

Abstract Motivated by the observation that vortex flow structure was evident in the energy loss at the surcharged junction manhole due to changes of hydraulic and geometrical parameters, a physical model was used to calculate energy loss coefficients and investigate the relationship between flow structure and energy loss at the surcharged three-way junction manhole. The effects of the flow discharge ratio, the connected angle between two inflow pipes, the manhole geometry, and the downstream water depth on the energy loss were analyzed based on the quantified energy loss coefficients and the identified flow structure. Moreover, two empirical formulae for head loss coefficients were validated by the experimental data. Results indicate that the effect of flow discharge ratio and connected angle are significant, while the effect of downstream water depth is not obvious. With the increase of the lateral inflow discharge, the flow velocity distribution and vortex structure are both enhanced. It is also found that a circular manhole can reduce local energy loss when compared to a square manhole. In addition, the tested empirical formulae can reproduce the trend of total head loss coefficient.

Study on Hydraulic Flow in Stratified Pipe Performed by Numerical Simulation

2018 ◽  
Vol 881 ◽  
pp. 3-14
Author(s):  
Ani Hairani ◽  
Djoko Legono ◽  
Adam Pamudji Rahardjo
Keyword(s):  
Reynolds Number ◽  
Flow Pattern ◽  
Flow Behavior ◽  
Area Ratio ◽  
Separation Flow ◽  
Wall Function ◽  
Road Tunnel ◽  
Three Dimensional Model ◽  
Straight Pipe ◽  
Pipe Model

An idea of introducing an underground floodway inspired by Storm-water Management and Road Tunnel (SMART) in Malaysia is considered attractive to minimize land utilization regarding to the flood problem in Jakarta. This research was aimed to know the flow behavior of this modified tunnel due to sudden transitions, pressure losses and loss coefficients using numerical modeling. The simulation was conducted in the three-dimensional model using FLUENT Software which was divided into three models, i.e., contraction, enlargement, and straight pipe model. The simulation model was followed the geometrical design of SMART which the area ratio between smaller and larger pipe, A1/A2 varied, namely 0.20, 0.50, and 0.80. Standard k-ε and equilibrium wall function were used in straight pipe model, while contraction and enlargement model used k-ε modified and non-equilibrium wall function. The effect of different Reynolds number was also studied in this research. The result of the simulation showed that hydraulic parameters and area ratio of sudden transitions pipe give significant effect towards losses along the pipe. FLUENT simulation result gave good agreement with Darcy-Weisbach formula. The results indicate that loss coefficient decreases with the increase in pipe area ratio. The increase in pressure head loss was incurred by severe separated regions in the vicinity of pipe transition which was proved by typical flow pattern. Variation of Reynolds number also showed a different area of separation flow, yet the flow pattern was somewhat similar.

scholarly journals Performance of a groyne in controlling flow, sediment and morphology around a tributary confluence

2018 ◽  
Vol 40 ◽  
pp. 04006
Author(s):  
Kohji Michioku ◽  
Yuki Osawa ◽  
Keiichi Kanda
Keyword(s):  
Morphological Changes ◽  
Main Channel ◽  
Original Position ◽  
River Morphology ◽  
Excellent Performance ◽  
Middle Stream ◽  
Sedimentary Deposit ◽  
And Migration ◽  
Flood Flow

In a middle stream reach, irreversible morphological changes are observed such as growth of a huge sandbar in front of the confluence, thalweg migration from the left to right bank, erosion of the main channel and sedimentary deposit on the floodplain. As a countermeasure against such degradation of river morphology, a groyne was constructed beneath the tributary confluence. Performance of a groyne in controlling flood flow, sediment transport and river morphology was investigated by a twodimensional hydrodynamic model. The analysis on twenty years of morphological change indicates that the groyne has an excellent performance in improving quality of river morphology such as reduction of the sandbar development and migration of the thalweg to the original position.

An experimental investigation of the oil film distribution in an oil–gas cyclone separator

2016 ◽  
Vol 231 (1) ◽  
pp. 14-25 ◽  
Author(s):  
Lingzi Wang ◽  
Jianmei Feng ◽  
Shijing Xu ◽  
Xiang Gao ◽  
Xueyuan Peng
Keyword(s):  
Flow Pattern ◽  
Pressure Loss ◽  
Film Flow ◽  
Separation Efficiency ◽  
Flow Behavior ◽  
Outer Cylinder ◽  
Cylinder Wall ◽  
Cyclone Separator ◽  
Oil Film ◽  
Oil Gas

The film flow behavior in an oil–gas cyclone separator was experimentally studied to improve the separation efficiency in terms of the effect of the oil film on the cylinder wall. The oil film flow pattern was captured using a high-speed camera, and the cylinder wall was divided into seven regions to analyze according to the different oil film flow patterns. Along the cyclone cylinder height, the central part of the cylinder was the main flow area, in which droplet–wall collisions and oil film splashing were severe. Additionally, the oil film’s distribution characteristics under inlet velocities of 14.0, 16.0, and 18.0 m/s were compared, and the results showed that more splashing oil droplets were generated under higher inlet velocity. Moreover, changing the structure of the central channel and outer cylinder slightly changed the oil film’s area and flow pattern but exhibited a weak effect on the oil film thickness and re-entrainment. Then, an improved structure was proposed by adding a porous cylinder to the outer cyclone to avoid the generation of small splashing droplets from the oil film. The performance of the modified separator was measured in a real oil-injected compressor system, which demonstrated higher separation efficiency with no increase in static pressure loss. The separation efficiency increased by up to 2.7%, while the pressure loss decreased by up to 10%. Thus, the improved structure can improve the performance of oil–gas separators by changing the distribution and thickness of the oil film on the cylinder wall.

A New Model for Dispersed Multi-Layer Oil-Water Flow

2001 ◽  
Author(s):  
Subash S. Jayawardena ◽  
Banu Alkaya ◽  
Clifford L. Redus ◽  
James P. Brill
Keyword(s):  
Flow Pattern ◽  
Fluid Model ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Homogeneous Model ◽  
Flow Patterns ◽  
New Model ◽  
Oil In Water ◽  
Oil Water ◽  
Liquid Flows

Abstract Flow patterns observed in near-horizontal oil-water two-phase flows are quite different from those in gas-liquid flows. Experience with gas-liquid flows suggests that the mechanisms governing the flow behavior are flow-pattern dependent. However, little attention has been given to modeling flow patterns observed only in liquid-liquid systems. Such flow patterns include an oil-in-water dispersion flowing on top of a water layer and the simultaneous flow of dispersions of water-in-oil and oil-in-water as separate layers. A new mechanistic model is developed for one such flow pattern in horizontal and near-horizontal pipelines. The model combined the two-fluid model used for stratified flows with the homogeneous model used for dispersed flows. This paper presents that model, and shows that the new model can predict the pressure gradient as well as the holdup. The model results are compared with those from two other models, the stratified flow model and the homogeneous model. The new model predictions are also compared with available experimental data.

Control of Separation Zone Behind a Flat Plate Under the Ground Effect Using Porous Lamination, Mathematical Modeling

2020 ◽  
pp. 2050109
Author(s):  
Kazem Reza-Asl ◽  
Saeed Foshat
Keyword(s):  
Vortex Shedding ◽  
Vortex Structure ◽  
Lift Force ◽  
Liquid Surface ◽  
Separation Zone ◽  
Flow Behavior ◽  
Ground Effect ◽  
The Body ◽  
Numerical Code ◽  
Porous Zone

Examination of the flat and curved plates flying close to the ground is an appropriate approach in understanding the complexity of flow behavior near a solid or liquid surface. When a body flies close to a surface, the vortex structure behind the body is changed; therefore, the resultant lift force is more than zero. This phenomenon is named “ground effect”. In this study, flat and curved plates submerged in the ground boundary layer were numerically investigated under the ground effect. After validating the desired numerical code, the influences of adding porous layer to the plates with [Formula: see text] attack angle were examined on vortex structure and flow separation behind the plate under the ground effect. The obtained results revealed that using a porous zone significantly reduced the separation zone and changed the vortex shedding structure downstream of the plates.

scholarly journals Tributary Channel Width Effect on the Flow Behavior in Trapezoidal and Rectangular Channel Confluences

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1344
Author(s):  
Aliasghar Azma ◽  
Yongxiang Zhang
Keyword(s):  
Recirculation Zone ◽  
Flow Behavior ◽  
Rectangular Channel ◽  
Maximum Velocity ◽  
Main Channel ◽  
Channel Width ◽  
Width Ratio ◽  
Geometrical Shape ◽  
Eddy Simulation ◽  
Flow Parameters

Channel confluences happen commonly in water transport networks and natural rivers. Utilizing a 3D CFD code, a series of numerical simulations were performed using a large eddy simulation turbulence model to investigate the effect of the variations in tributary channel width and the transverse geometrical shape of the main channel on the flow parameters and vertical structure in a T-shape confluence. The code was calibrated using the experimental data from the literature. Flow parameters were considered in ratios of tributary width to the main channel width in trapezoidal and rectangular channels. Results indicate that decreasing the width ratio of the tributary channel to the main channel significantly affects the flow structure in the confluence. Generally, it increases the width and length of the main recirculation zone. It also increases the maximum velocity near the bed, especially in cases with a trapezoidal shape. Besides, it highly affects the structure and formation of the recirculation zone in trapezoidal channels.

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