Theory of the Maxwell effect for large velocity gradients

1990 ◽  
Vol 50 (5) ◽  
pp. 1831-1833
Author(s):  
I. B. Aizenberg
Keyword(s):  
Velocity Gradients ◽  
Large Velocity ◽  
Maxwell Effect

The Influence of Boundary Layer Velocity Gradients and Bed Proximity on Vortex Shedding From Free Spanning Pipelines

1984 ◽  
Vol 106 (1) ◽  
pp. 70-78 ◽  
Author(s):  
A. J. Grass ◽  
P. W. J. Raven ◽  
R. J. Stuart ◽  
J. A. Bray
Keyword(s):  
Boundary Layer ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Combined Effects ◽  
Maximum Increase ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Layer Velocity ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

The paper summarizes the results of a laboratory study of the separate and combined effects of bed proximity and large velocity gradients on the frequency of vortex shedding from pipeline spans immersed in the thick boundary layers of tidal currents. This investigation forms part of a wider project concerned with the assessment of span stability. The measurements show that in the case of both sheared and uniform approach flows, with and without velocity gradients, respectively, the Strouhal number defining the vortex shedding frequency progressively increases as the gap between the pipe base and the bed is reduced below two pipe diameters. The maximum increase in vortex shedding Strouhal number, recorded close to the bed in an approach flow with large velocity gradients, was of the order of 25 percent.

scholarly journals High-resolution, near-IR spectroscopy and imaging of the Egg and Rotten Egg nebulae (AFGL 2688 and OH 231.8+4.2)

1999 ◽  
Vol 191 ◽  
pp. 431-436
Author(s):  
Joel H. Kastner ◽  
LeeAnn Henn ◽  
David A. Weintraub ◽  
Ian Gatley
Keyword(s):  
Near Infrared ◽  
Polar Axis ◽  
Central Star ◽  
Infrared Images ◽  
Near Ir ◽  
Velocity Gradients ◽  
Mira Variable ◽  
Model Combining ◽  
Large Velocity ◽  
Spherical Expansion

Velocity-resolved 2.12 μm H2 maps of the Egg Nebula (AFGL 2688), obtained with the NOAO Phoenix spectrometer, elaborate on previous observations of large velocity gradients in molecular emission both along and perpendicular to the polar axis of the system. The measured gradients along the polar axis support the notion that the polar H2 emission regions are formed in shocks as fast, collimated winds collide with material ejected while the central star was still on the AGB. The kinematics of H2 emission along the equatorial plane, meanwhile, are consistent with a model combining spherical expansion with rotation about the polar axis, although a model invoking multiple outflow axes cannot be ruled out.We also obtained the first direct near-infrared images of QX Pup, a Mira variable embedded within the evolved bipolar nebula OH 231.8+4.2. The inferred absolute K magnitude of the central Mira appears “normal” given its ∼ 700 day period, which is remarkable in light of its position at the heart of such an unusual object.

Linear polarization of millimeter-wave emission lines in clouds without large velocity gradients

1988 ◽  
Vol 328 ◽  
pp. 304 ◽  
Author(s):  
D. C. Lis ◽  
P. F. Goldsmith ◽  
R. L. Dickman ◽  
C. R. Predmore ◽  
A. Omont ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Linear Polarization ◽  
Emission Lines ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Wave Emission

scholarly journals Molecular loops in the Galactic centre; evidence for magnetic floatation accelerating molecular gas

2006 ◽  
Vol 2 (S237) ◽  
pp. 501-501
Author(s):  
H. Yamamoto ◽  
Y. Fukui ◽  
M. Fujishita ◽  
K. Torii ◽  
N. Kudo ◽  
...  
Keyword(s):  
Galactic Center ◽  
Galactic Plane ◽  
Scale Height ◽  
Galactic Centre ◽  
Molecular Gas ◽  
Molecular Image ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Loop 2

The new molecular image obtained by NANTEN telescope in the galactic center has revealed the existence of the two loop like structures, loop 1 and loop 2, which have never been seen before toward l = 355° to 358°. The velocities of loop 1 and loop 2 are −180 to −90 km s−1 and −90 and −40 km s−1, respectively, and these two loops have strong velocity gradients. The foot points of the loops show a very broad linewidth of ~40 to 80 km s−1 whose large velocity spans are characteristic of the molecular gas near the galactic center. Therefore, we classified the loops as being located in the galactic center and adopt a distance of 8.5 kpc. Then, the projected lengths of loop 1 and loop 2 were estimated as ~500 and ~300 pc, respectively and velocity gradients corresponds to ~80 km s−1 per 250 pc along loop 1 and ~60 km s−1 per 150 pc along loop 2. The heights of these loops are also estimated as ~220 to ~300 pc from the galactic plane, significantly higher than the typical scale height in the nuclear disk.

Boundary Layers

2018 ◽  
Author(s):  
S. G. Rajeev
Keyword(s):  
Boundary Layer ◽  
Fluid Velocity ◽  
One Dimension ◽  
Navier Stokes ◽  
Analytic Approximation ◽  
Navier Stokes Equation ◽  
Velocity Gradients ◽  
Thin Region ◽  
Large Velocity ◽  
Different Dimensions

It is found experimentally that all the components of fluid velocity (not just thenormal component) vanish at a wall. No matter how small the viscosity, the large velocity gradients near a wall invalidate Euler’s equations. Prandtl proposed that viscosity has negligible effect except near a thin region near a wall. Prandtl’s equations simplify the Navier-Stokes equation in this boundary layer, by ignoring one dimension. They have an unusual scale invariance in which the distances along the boundary and perpendicular to it have different dimensions. Using this symmetry, Blasius reduced Prandtl’s equations to one dimension. They can then be solved numerically. A convergent analytic approximation was also found by H. Weyl. The drag on a flat plate can now be derived, resolving d’Alembert’s paradox. When the boundary is too long, Prandtl’s theory breaks down: the boundary layer becomes turbulent or separates from the wall.

X-Ray Line Transfer in Plasmas with Large Velocity Gradients

2005 ◽  
pp. 171-176
Author(s):  
F.M. Kerr ◽  
A. Gouveia ◽  
R.W. Lee ◽  
P.K. Patel ◽  
O. Renner ◽  
...  
Keyword(s):  
X Ray ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Line Transfer

X-Ray Line Transfer in Plasmas with Large Velocity Gradients

2005 ◽  
Vol 298 (1-2) ◽  
pp. 171-176 ◽  
Author(s):  
F. M. Kerr ◽  
A. Gouveia ◽  
R. W. Lee ◽  
P. K. Patel ◽  
O. Renner ◽  
...  
Keyword(s):  
X Ray ◽  
Velocity Gradients ◽  
Large Velocity ◽  
Line Transfer
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