Study on the Effect of Guide Wall on the Transverse Velocity in the Bend

2020 ◽  
Author(s):  
Jing Zhang ◽  
Tiantian Wang ◽  
Qinghua Zhang
Keyword(s):  
Transverse Velocity ◽  
Guide Wall

Modelling Techniques in Applied Glaciology: Numerical Modelling of Avalanches

1983 ◽  
Vol 4 ◽  
pp. 297-297
Author(s):  
G. Brugnot
Keyword(s):  
Finite Difference Method ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Momentum Conservation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Modelling Techniques ◽  
Reference Grid ◽  
The One ◽  
Near Future

We consider the paper by Brugnot and Pochat (1981), which describes a one-dimensional model applied to a snow avalanche. The main advance made here is the introduction of the second dimension in the runout zone. Indeed, in the channelled course, we still use the one-dimensional model, but, when the avalanche spreads before stopping, we apply a (x, y) grid on the ground and six equations have to be solved: (1) for the avalanche body, one equation for continuity and two equations for momentum conservation, and (2) at the front, one equation for continuity and two equations for momentum conservation. We suppose the front to be a mobile jump, with longitudinal velocity varying more rapidly than transverse velocity.We solve these equations by a finite difference method. This involves many topological problems, due to the actual position of the front, which is defined by its intersection with the reference grid (SI, YJ). In the near future our two directions of research will be testing the code on actual avalanches and improving it by trying to make it cheaper without impairing its accuracy.

Measurements of the Ion Transverse Velocity Distribution in the Gap of an Ion Beam Diode

1986 ◽  
Author(s):  
Y. Maron ◽  
M. D. Coleman ◽  
D. A. Hammer ◽  
H. S. Peng
Keyword(s):  
Velocity Distribution ◽  
Ion Beam ◽  
Transverse Velocity

scholarly journals Discontinuities in a Transverse Velocity Profile of a Valley Glacier Measured by Photogrammetry

1989 ◽  
Vol 12 ◽  
pp. 89-91 ◽  
Author(s):  
W. Kick
Keyword(s):  
Velocity Profile ◽  
Single Unit ◽  
Transverse Velocity ◽  
Short Term ◽  
En Bloc ◽  
Block Motion ◽  
Valley Glacier ◽  
Unit Block ◽  
Time Periods ◽  
Shear Planes

The surface movement of part of a Nanga Parbat (Himalaya) glacier immediately below an ice fall has been investigated by terrestrial stereophotogrammetry. This method provides an opportunity of measuring many more points than by using other procedures. The shape of the transverse velocity profile indicated normal stream-like flow and not “blockschollen movement”, as might have been expected, because of its high velocity (45 cm/d). But, one feature of the ice fall above had been carried down-glacier to the location of the profile; namely, several discontinuities along the velocity diagram. The ice fall had transmitted a small part of its splitting into seracs to the flatter area below, but not its blockschollen movement. There seems to be a contradiction in that on one side there are discontinuities, i.e. the glacier is torn up into blocks by shear planes, but on the other side the glacier moves en bloc. In fact, a short-term investigation over hours or just a few days discloses cracks but, after time periods of a week or more, these irregularities compensate for one another so that they merge into a single unit block motion.

Vortex shedding from a circular cylinder in moderate-Reynolds-number shear flow

1980 ◽  
Vol 101 (4) ◽  
pp. 721-735 ◽  
Author(s):  
Masaru Kiya ◽  
Hisataka Tamura ◽  
Mikio Arie
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Transverse Velocity ◽  
Number Range ◽  
Uniform Shear ◽  
Reynolds Number Range ◽  
Moderate Reynolds Number ◽  
Shear Parameter

The frequency of vortex shedding from a circular cylinder in a uniform shear flow and the flow patterns around it were experimentally investigated. The Reynolds number Re, which was defined in terms of the cylinder diameter and the approaching velocity at its centre, ranged from 35 to 1500. The shear parameter, which is the transverse velocity gradient of the shear flow non-dimensionalized by the above two quantities, was varied from 0 to 0·25. The critical Reynolds number beyond which vortex shedding from the cylinder occurred was found to be higher than that for a uniform stream and increased approximately linearly with increasing shear parameter when it was larger than about 0·06. In the Reynolds-number range 43 < Re < 220, the vortex shedding disappeared for sufficiently large shear parameters. Moreover, in the Reynolds-number range 100 < Re < 1000, the Strouhal number increased as the shear parameter increased beyond about 0·1.

scholarly journals The most massive white dwarfs in the solar neighbourhood

2021 ◽  
Vol 503 (4) ◽  
pp. 5397-5408
Author(s):  
Mukremin Kilic ◽  
P Bergeron ◽  
Simon Blouin ◽  
A Bédard
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Transverse Velocity ◽  
Maximum Mass ◽  
Model Calculations ◽  
Rapid Rotation ◽  
Rotation Rates ◽  
Binary Mergers ◽  
Chandrasekhar Limit

ABSTRACT We present an analysis of the most massive white dwarf candidates in the Montreal White Dwarf Database 100 pc sample. We identify 25 objects that would be more massive than $1.3\, {\rm M}_{\odot }$ if they had pure H atmospheres and CO cores, including two outliers with unusually high photometric mass estimates near the Chandrasekhar limit. We provide follow-up spectroscopy of these two white dwarfs and show that they are indeed significantly below this limit. We expand our model calculations for CO core white dwarfs up to M = 1.334 M⊙, which corresponds to the high-density limit of our equation-of-state tables, ρ = 109 g cm−3. We find many objects close to this maximum mass of our CO core models. A significant fraction of ultramassive white dwarfs are predicted to form through binary mergers. Merger populations can reveal themselves through their kinematics, magnetism, or rapid rotation rates. We identify four outliers in transverse velocity, four likely magnetic white dwarfs (one of which is also an outlier in transverse velocity), and one with rapid rotation, indicating that at least 8 of the 25 ultramassive white dwarfs in our sample are likely merger products.

A radio jet associated with the symbiotic star CH Cygni

1986 ◽  
Vol 64 (4) ◽  
pp. 520-522 ◽  
Author(s):  
E. R. Seaquist ◽  
A. R. Taylor
Keyword(s):  
Electron Density ◽  
White Dwarf ◽  
Transverse Velocity ◽  
Stellar Object ◽  
Symbiotic Star ◽  
Ionized Gas ◽  
Radio Outburst ◽  
Supercritical Accretion ◽  
End To End ◽  
Red Giant

We present observations that show that the symbiotic star CH Cygni recently underwent a strong radio outburst that produced a radio-emitting thermal jet. The jet is two-sided and is expanding lengthwise at an observed rate (end to end) of 1 arcsec/year, corresponding to a transverse velocity of 1100 km∙s−1 in each direction. The electron density on January 22, 1985 exceeded 2 × 106 cm−3, and the mass of the (ionized) gas exceeded [Formula: see text]. The emergence of the jet coincided with a decline in the visual luminosity of [Formula: see text].The data are consistent with a jet produced by supercritical accretion in a binary containing a red giant and a [Formula: see text] white dwarf. The discovery of a jet in such a system provides confirming evidence of the role played by accretion in determining the optical and radio properties of this system. It is also the first expanding jet found to be associated with an evolved stellar object.

scholarly journals Added mass of a circular cylinder oscillating in a free stream

2013 ◽  
Vol 469 (2156) ◽  
pp. 20130135 ◽  
Author(s):  
Efstathios Konstantinidis
Keyword(s):  
Circular Cylinder ◽  
Free Stream ◽  
Transverse Velocity ◽  
Inertial Force ◽  
Added Mass ◽  
Stream Velocity ◽  
Virtual Experiment ◽  
Classical Formulation ◽  
Fundamental Understanding ◽  
Two Dimensional Flow

The fundamental understanding of the added mass phenomenon associated with the motion of a solid body relative to a fluid is revisited. This paper focuses on the two-dimensional flow around a circular cylinder oscillating transversely in a free stream. A virtual experiment reveals that the classical approach to this problem leads to a paradox. The inertial force is derived afresh based on analysis of the motion in a frame of reference attached to the cylinder centroid, which overcomes the paradox in the classical formulation. It is shown that the inertial force depends not only on the acceleration of the cylinder per se , but also on the relative motion between body and fluid embodied in a parameter called alpha, α , which represents the ratio of the maximum transverse velocity of the cylinder to the free-stream velocity; the induced inertial force is directionally varying and non-harmonic in time depended on the alpha parameter. It is further shown that the component of the inertial force in the transverse direction is negligible for α <0.1, increases quadratically for α <0.5, and tends asymptotically to the classical result as , i.e. in still fluid.

scholarly journals Fuzzy rules based model for solute dispersion in an open channel dead zone

2002 ◽  
Vol 4 (1) ◽  
pp. 39-51
Author(s):  
Helen Kettle ◽  
Keith Beven ◽  
Barry Hankin
Keyword(s):  
Finite Volume ◽  
Fuzzy Number ◽  
Open Channel ◽  
Transverse Velocity ◽  
Dead Zone ◽  
Fuzzy Rules ◽  
Turbulent Velocity ◽  
Velocity Fluctuations ◽  
Laboratory Flume ◽  
The Mean

A method has been developed to estimate turbulent dispersion based on fuzzy rules that use local transverse velocity shears to predict turbulent velocity fluctuations. Turbulence measurements of flow around a rectangular dead zone in an open channel laboratory flume were conducted using an acoustic Doppler velocimeter (ADV) probe. The mean velocity and turbulence characteristics in and around the shear zone were analysed for different flows and geometries. Relationships between the mean transverse velocity shear and the turbulent velocity fluctuations are encapsulated in a simple set of fuzzy rules. The rules are included in a steady-state hybrid finite-volume advection–diffusion scheme to simulate the mixing of hot water in an open-channel dead zone. The fuzzy rules produce a fuzzy number for the magnitude of the average velocity fluctuation at each cell boundary. These are then combined within the finite-volume model using the single-value simulation method to give a fuzzy number for the temperature in each cell. The results are compared with laboratory flume data and a computational fluid dynamics (CFD) simulation from PHOENICS. The fuzzy model compares favourably with the experiment data and offers an alternative to traditional CFD models.

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