scholarly journals Distribution of velocity and temperature between concentric rotating cylinders

1935 ◽  
Vol 151 (874) ◽  
pp. 494-512 ◽  
Keyword(s):  
Turbulent Flow ◽  
Velocity Distribution ◽  
The Other ◽  
Momentum Transport ◽  
Rotating Cylinders ◽  
Simultaneous Measurements ◽  
Other Hand ◽  
Vorticity Transport

It is not possible to distinguish between the Momentum Transport and the Vorticity Transport theories of turbulent flow by measurements of the distribution of velocity in a fluid flowing under pressure through pipes or between parallel planes. Only simultaneous measurements of temperature and velocity distribution are capable of distinguishing between the two theories in these cases. On the other hand, it will be seen later that measurements of the distribution of velocity between concentric rotating cylinders are capable of distinguishing between the two theories; in fact the predictions of the two theories in this case are sharply contrasted and mutually exclusive.

On Turbulent Flow Between Parallel Plates

1953 ◽  
Vol 20 (1) ◽  
pp. 109-114
Author(s):  
S. I. Pai
Keyword(s):  
Turbulent Flow ◽  
Velocity Distribution ◽  
Poiseuille Flow ◽  
The Other ◽  
Turbulent Velocity ◽  
Parallel Plates ◽  
Mean Velocity ◽  
Reynolds Equations ◽  
Mean Pressure ◽  
The Mean

Abstract The Reynolds equations of motion of turbulent flow of incompressible fluid have been studied for turbulent flow between parallel plates. The number of these equations is finally reduced to two. One of these consists of mean velocity and correlation between transverse and longitudinal turbulent-velocity fluctuations u 1 ′ u 2 ′ ¯ only. The other consists of the mean pressure and transverse turbulent-velocity intensity. Some conclusions about the mean pressure distribution and turbulent fluctuations are drawn. These equations are applied to two special cases: One is Poiseuille flow in which both plates are at rest and the other is Couette flow in which one plate is at rest and the other is moving with constant velocity. The mean velocity distribution and the correlation u 1 ′ u 2 ′ ¯ can be expressed in a form of polynomial of the co-ordinate in the direction perpendicular to the plates, with the ratio of shearing stress on the plate to that of the corresponding laminar flow of the same maximum velocity as a parameter. These expressions hold true all the way across the plates, i.e., both the turbulent region and viscous layer including the laminar sublayer. These expressions for Poiseuille flow have been checked with experimental data of Laufer fairly well. It also shows that the logarithmic mean velocity distribution is not a rigorous solution of Reynolds equations.

scholarly journals Interpretation of velocity distribution of the inner regions of the Galaxy

1964 ◽  
Vol 20 ◽  
pp. 195-199 ◽  
Author(s):  
G. de Vaucouleurs
Keyword(s):  
Velocity Distribution ◽  
Spiral Structure ◽  
The Other ◽  
Galactic Centre ◽  
Line Profiles ◽  
Spiral Pattern ◽  
Other Hand ◽  
The Galaxy

I. The large positive and negative velocities in the 21-cm line profiles near the galactic centre have indicated the presence of substantial departures from circular motions in the central parts of the Galaxy. The Leiden astronomers (Oort and Rougoor 1958; Rougoor and Oort 1960) have interpreted these observations in terms of an “expanding arm” at a mean distance of about 3 kpc from the centre. It is not clear how these arms or arcs are related to the regular spiral structure, if the Galaxy is an ordinary spiral similar to M31 as commonly assumed. If, on the other hand, the Galaxy is similar to the SAB(r) or SAB(rs) systems, as suggested by the multiplicity of the spiral pattern discussed in another communication, a different interpretation of the velocity distribution is possible.

Hydraulics of culvert fishways V: Alberta fish weirs and baffles

1990 ◽  
Vol 17 (6) ◽  
pp. 1015-1021 ◽  
Author(s):  
N. Rajaratnam ◽  
C. Katopodis ◽  
M. A. Fairbairn
Keyword(s):  
Turbulent Flow ◽  
Key Words ◽  
Channel Flow ◽  
Laboratory Study ◽  
Open Channel ◽  
Open Channel Flow ◽  
Hydraulic Performance ◽  
The Other ◽  
Other Hand ◽  
Flow Hydraulics

This paper presents the results of a laboratory study of the hydraulic performance of fish weirs and fish baffles used by Alberta Transportation for improving the fish-passing capacity of culverts. It was found that if the longitudinal spacing of the weirs is limited to 0.6 and 1.2 times the diameter of the culvert, their performance is comparable to that of the corresponding weir and slotted-weir baffle systems, with regard to the depth of pool between the baffles as well as the barrier velocity. On the other hand, the fish baffles did not perform as well as the fish weirs under the conditions tested. Key words: culverts, fishways, baffles, turbulent flow, hydraulics, open-channel flow.

The Axial Frictional Resistance of Long Cylinders in Turbulent Flow

1959 ◽  
Vol 3 (03) ◽  
pp. 24-28
Author(s):  
K. Karhan
Keyword(s):  
Turbulent Flow ◽  
Flat Plate ◽  
Frictional Resistance ◽  
The Other ◽  
Ship Model ◽  
Transverse Curvature ◽  
Other Hand ◽  
Length And Area ◽  
Mathematical Relations

In ship-model extrapolation the frictional resistance of the ship surface is generally taken to be equal to that of the flat plate having the same length and area. Experiments carried out at several laboratories with models of different size show dearly that each model should have its own extrapolation curve. In spite of general agreement that this is so, the flat-plate extrapolation curve is still generally used. On the other hand it is not easy to derive mathematical relations for ship-form frictional resistance or to make extensive experiments for this purpose. It is obvious that a first step towards departing from the flat-plate resistance basis should be to study the effect of transverse curvature on frictional resistance.

Numerical Study of Flow Through 3x3 Multiswirler Arrays With Co and Counter Swirler Arrangements

2015 ◽  
Author(s):  
Prachi Rojatkar ◽  
Milind A. Jog ◽  
San-Mou Jeng
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Velocity Gradient ◽  
Recirculation Zone ◽  
Numerical Study ◽  
The Other ◽  
Combustion Performance ◽  
Other Hand ◽  
Flow Through

A numerical study of turbulent flow through 3×3 multi swirler arrangement has been performed using the realizable k-ε turbulence model on a grid with about 19 million points. All co and alternate co/counter swirler configurations comprised of radial-radial swirler with counter rotating vanes are analyzed. The offset distances of swirler exit from the base wall of confinement of 0.02D and 0.31D are considered where D is the diameter of swirler exit. For both arrangements, a strong jet is issued as the flow exits individual swirl cup. Recirculation is observed at the walls and between each swirl cup along with the formation of central toroidal recirculation zone (CTRZ) at each individual swirler. It is observed that all co swirling arrangement has a stronger more compact individual CTRZ. On the other hand alternate co and counter arrangement produces more swirler-to-swirler interactions. When the offset between swirler exit and base wall of confinement is increased to 0.31D, longer but more compact CTRZ are formed at each swirler cup. The velocity gradient for 0.31D offset case is also higher than that of 0.02D. These differences in the flow field indicate better combustion performance, fuel breakup and flame anchoring for the higher offset case.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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