scholarly journals Hybrid modelling of low velocity zones in an asymmetrical channel with sidewall longitudinal rib to assist fish passage

2020 ◽  
Vol 36 (5) ◽  
pp. 807-818 ◽  
Author(s):  
Pedro X. Sanchez ◽  
Xinqian Leng ◽  
Johann Von Brandis‐Martini ◽  
Hubert Chanson
Keyword(s):  
Fish Passage ◽  
Low Velocity ◽  
Hybrid Modelling

Characterizing low velocity zones around a spoiler baffle for improving fish passage performance

2020 ◽  
pp. 1837-1842
Author(s):  
D. Magaju ◽  
H. Friedrich ◽  
P. Franklin ◽  
C. Baker ◽  
J. Montgomery
Keyword(s):  
Fish Passage ◽  
Low Velocity

Numerical study of an innovative fish ladder design for perched culverts

2016 ◽  
Vol 43 (2) ◽  
pp. 173-181 ◽  
Author(s):  
Jason M. Duguay ◽  
R.W. Jay Lacey
Keyword(s):  
Recirculation Zone ◽  
Numerical Study ◽  
Fish Habitat ◽  
Fish Passage ◽  
Dynamics Model ◽  
Low Velocity ◽  
Computational Fluid Dynamics Model ◽  
Fish Ladder ◽  
Physical Prototype ◽  
High Flows

A fish ladder designed to facilitate fish passage at the outlet end of perched culverts is investigated with a 3D computational fluid dynamics model. The fish ladder consists of a series of alternating arch baffles with geometries providing options for fish passage over varying flow and debris conditions within the ladder. At high flows, the baffle’s protruding center arch increases pool depth, reducing the volumetric bulk turbulence of the pools and improving fish habitat. The arch baffle is compared to a standard baffle design currently in use and demonstrates potential advantages for fish passage. A recirculation zone of low velocity occupies a large volume of the pool believed to provide appropriate hydraulic habitat for resting and staging jump attempts upstream. This numerical study provides an acceptable design for future physical prototype testing in the laboratory or field to verify hydraulics and evaluate fish passage effectiveness.

Velocity distributions near the inlet of corrugated steel pipe culverts

2012 ◽  
Vol 39 (12) ◽  
pp. 1243-1251 ◽  
Author(s):  
Martin Hunt ◽  
Shawn Clark ◽  
Rob Tkach
Keyword(s):  
Velocity Field ◽  
Recirculation Zone ◽  
Velocity Structure ◽  
Three Dimensional ◽  
Shear Zones ◽  
Fish Passage ◽  
Steel Pipe ◽  
Low Velocity ◽  
Velocity Flow ◽  
Percent Area

This paper presents the findings of a study examining the velocity field within the inlet region of a corrugated steel pipe (CSP) culvert model with vertical headwall, 45° wingwall, and projecting end inlet treatments. Also examined are the effects of embedding the culvert below the stream bed and backfilling the culvert with granular material. Three-dimensional velocity distributions were measured in an effort to better understand how these inlet treatments may affect fish passage. The study examined velocity structure within a CSP culvert with a diameter of 0.8 m at a flow rate of 0.175 m3/s. Measurements were recorded using acoustic Doppler velocimeters at four locations; 0.25, 0.5, 1, and 2 diameters downstream of the inlet. The velocity field of each inlet configuration was dominated by a central jet of high velocity flow surrounded by a low velocity recirculation zone. Analysis of the percent area less than Uavg for each inlet treatment found that the projecting end configuration contained the largest low velocity zone. The usefulness of the low velocity recirculation zone as a fish passage corridor may however be limited by the presence of significant vertical and spanwise velocities as well as high shear zones.

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

Atomic orientation effects in proton stopping at low velocity

1983 ◽  
Vol 41 ◽  
pp. 708-709
Author(s):  
Kin Lam
Keyword(s):  
Polycrystalline Material ◽  
Charged Particles ◽  
Target Material ◽  
Stopping Power ◽  
Low Velocity ◽  
Electronic Density ◽  
Interatomic Distances ◽  
Frame Work ◽  
Image Position ◽  
Atomic Orientation

The energy of moving ions in solid is dependent on the electronic density as well as the atomic structural properties of the target material. These factors contribute to the observable effects in polycrystalline material using the scanning ion microscope. Here we outline a method to investigate the dependence of low velocity proton stopping on interatomic distances and orientations.The interaction of charged particles with atoms in the frame work of the Fermi gas model was proposed by Lindhard. For a system of atoms, the electronic Lindhard stopping power can be generalized to the formwhere the stopping power function is defined as

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