scholarly journals Detailed analysis of the wake and free-flow characteristics at the Goodnoe Hills MOD-2 site

1989 ◽  
Author(s):  
D.L. Elliott ◽  
J.C. Barnard
Keyword(s):  
Detailed Analysis ◽  
Flow Characteristics ◽  
Free Flow

scholarly journals Impact of Different Vegetation Zones on the Velocity and Discharge of Open-Channel Flow

2021 ◽  
Author(s):  
Xiaonan Tang ◽  
Yutong Guan ◽  
Yuxiang Hu
Keyword(s):  
Shear Layer ◽  
Management Practices ◽  
Open Channel ◽  
Flow Characteristics ◽  
Flow Region ◽  
Free Flow ◽  
Flow Process ◽  
Riparian Management ◽  
Free Zone ◽  
Rigid Vegetation

Different types of vegetation widely exist in rivers and wetlands. The vegetation will affect the ecological environment and flow process, thus becoming increasingly significant in river engineering and aquatic environmental management. Previous research on vegetated flow is mainly to understand the flow structure of open channels with fully covered one-layer vegetation. However, vegetation often grows along a river bank and co-exists in different heights. The present paper presents experimental results about the flow characteristics of an open-channel with two sides covered by differently layered vegetation, focusing on the effect of vegetation on the velocity distribution and discharge. Two heights of dowels in 10 cm and 20 cm were used to simulate rigid vegetation and arranged in a linear form on both sides of a channel bed under emergent and fully submerged flow conditions. The velocity at different positions was obtained using ADV (Acoustic Doppler Velocimetry). Measured results demonstrate that there exists a shear layer between free-flow and vegetated zones, indicating that the flow transition occurs between fast-moving flow in the free zone and slowly obstructed flow in the vegetated zone and induces a high shear layer and transverse coherent vortices near the interface. Furthermore, compared with the emergent condition, the discharge through the free-flow region slightly decreases under full submerged conditions while the discharge in the vegetated region increases, indicating that the vegetation does not significantly change the discharge percentage in the free region. These findings on differently-layered vegetation would help riparian management practices to maintain healthy ecological and habitat zones.

scholarly journals Modeling and Computation of Flow in a Passage With 360° Turning and Multiple Airfoils

1991 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Numerical Modeling ◽  
Detailed Analysis ◽  
Flow Condition ◽  
Global Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
The Individual ◽  
Spiral Casing

Numerical modeling of the three-dimensional flows in a spiral casing of a hydraulic turbine, containing a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor), is made. The physical model is based on a novel two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

Pressure-flow characteristics of coronary collaterals in dogs

1989 ◽  
Vol 256 (2) ◽  
pp. H441-H445 ◽  
Author(s):  
K. W. Scheel ◽  
H. Mass ◽  
S. E. Williams
Keyword(s):  
Isolated Heart ◽  
Flow Characteristics ◽  
Back Pressure ◽  
Free Flow ◽  
Flow Index ◽  
Collateral Flow ◽  
Retrograde Flow ◽  
Pressure Flow ◽  
Flow Method ◽  
Pressure Method

In this study we utilized two methods to investigate the pressure-flow, P-F, relationship of the coronary collateral vessels in a beating, blood-perfused, isolated heart preparation. In the first method (free-flow method), 12 dog hearts were perfused at pressures ranging from 100 to 0 mmHg, whereas the retrograde flow (index of collateral flow) was measured on the circumflex coronary artery, LCA, against atmospheric pressure, first during autoregulation and then after maximum vasodilation. In the second method (back-pressure method), the back pressure to retrograde flow was varied from 0 to 100 mmHg, whereas the perfusion pressure to the remaining vessels was maintained constant at 100 mmHg. This procedure was performed on four hearts with and without embolization of the LCA by 25-microns spheres. The free-flow method demonstrated a linear P-F relationship with an average correlation coefficient, r, of 0.98. The pressure intercept was 1.7 +/- 1.2 mmHg. The back-pressure method yielded a relationship that was more curvilinear with an average pressure intercept of 13 mmHg without embolization and 38 mmHg with embolization. An analog of the coronary and collateral circulation was used to illustrate that, in the back-pressure method, changes in the coronary resistance at low pressures contributed to the nonlinearity of the collateral P-F characteristics and that the network formed between the collateral and coronary resistances was responsible for the higher pressure intercept value.

Switch Technology in Intelligent Substation

2013 ◽  
Vol 748 ◽  
pp. 468-472
Author(s):  
Xiang Qun Wang ◽  
Zeng Hua Zhang ◽  
He Wang ◽  
Chun Long Li ◽  
Xiao Yan Sun ◽  
...  
Keyword(s):  
Detailed Analysis ◽  
Network Topology ◽  
Data Flow ◽  
Flow Characteristics ◽  
Secondary System ◽  
Ring Network ◽  
Technical Application ◽  
Reliable Transmission ◽  
Network Program ◽  
Ethernet Switch

As the technology of intelligent substation is developed gradually, the significance of he Ethernet switch in the substation is obvious increasingly.Firstly, the learning and transmitting principle of Ethernet frame are introduced, then the network program of secondary system using the switch in the hierarchial structure is described. And then a detailed analysis of the VLAN, QoS, mirror and ring network is given, also the various technical application scheme are provided according to a variety of IED features and data flow characteristics. On the basis of the different business needs and different message types, the reasonable design of network topology and the flexible use of these switching technology , can support security, stability, reliable transmission of communication message in intelligent substation , therefore the whole substation becomes more strong.

scholarly journals Free Flow and Discharge Characteristics of Trapezoidal-Shaped Weirs

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 238
Author(s):  
Yebegaeshet T. Zerihun
Keyword(s):  
Free Surface ◽  
Current Knowledge ◽  
Flow Characteristics ◽  
Free Flow ◽  
Downstream Face ◽  
Large Set ◽  
Discharge Characteristics ◽  
Flow Discharge ◽  
Streamline Curvature ◽  
Surface Profiles

A number of studies have considered the effects of weir design variations on the free- and submerged-flow characteristics of trapezoidal broad-crested weirs. It appears that the hydraulics of short-crested weir flows have received little attention; thus, the current knowledge is incomplete. By systematically analyzing a large set of experimental data, the present study aims to fill in this knowledge gap and to provide a complete description of the discharge characteristics of trapezoidal-shaped weirs, including the salient features of two-dimensional weir flows. The analysis of the axial free-surface profiles for short-crested weir flows attested that the location of the nearest station for the correct measurement of the overflow depth under free-flow conditions is at η0  from the heel of the weir, where η0  is the upstream free-surface elevation. Additionally, an empirical equation for the free-flow discharge coefficient is proposed as being valid for a trapezoidal-shaped weir with varying upstream- and downstream-face slopes. The results of this investigation reveal that the streamline curvature and the slopes of the upstream and downstream weir faces significantly affect the streamwise flow patterns and, hence, the free-flow discharge.

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