Instabilities in smectics A submitted to an alternating shear flow. II. Experimental results

1983 ◽  
Vol 44 (6) ◽  
pp. 665-673 ◽  
Author(s):  
J. Marignan ◽  
O. Parodi
Keyword(s):  
Shear Flow ◽  
Experimental Results

The Development of the Reynolds Stress Tensor in a Turbulent Shear Flow

1970 ◽  
Vol 92 (4) ◽  
pp. 836-842
Author(s):  
S. J. Shamroth ◽  
H. G. Elrod
Keyword(s):  
Shear Flow ◽  
Stress Tensor ◽  
Linear Model ◽  
Reynolds Stress ◽  
Experimental Results ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Reynolds Stress Tensor ◽  
Theoretical Predictions

The development of the normalized Reynolds stress tensor, uiuj/q2, in the region upstream of a fully developed, turbulent shear flow is investigated. An inviscid, linear model is used to predict values of the normalized Reynolds stress tensor as a function of position. The theoretical predictions are then compared with experimental results.

scholarly journals Partial Strake Coverage Vortex-Induced Vibration Benchmarking Using SHEAR7v4.5

2009 ◽  
Author(s):  
Hayden Marcollo ◽  
J. Kim Vandiver
Keyword(s):  
Experimental Data ◽  
Shear Flow ◽  
Laboratory Data ◽  
Experimental Results ◽  
High Mode ◽  
Flow Conditions ◽  
Vortex Induced Vibration ◽  
Future Improvement

A VIV benchmarking study was undertaken using SHEAR7v4.5 against NDP high mode VIV response laboratory data. The purpose of which was to derive an improved set of modeling parameters for partial strake coverage cases whilst not comprising previous accuracy of shear flow bare riser response predictions. Fifty percent (50%) partial strake coverage experimental data was utilized from both uniform and shear flow conditions while bare data was also included in the activity for reference purposes. The results showed that such an activity can derive an improved set of modeling parameters that significantly improve the ability to match experimental results and also highlight where future improvement efforts can be targeted.

An experimental study of shear-enhanced convection in a mushy layer

2008 ◽  
Vol 612 ◽  
pp. 363-385 ◽  
Author(s):  
JEROME A. NEUFELD ◽  
J. S. WETTLAUFER
Keyword(s):  
Shear Flow ◽  
Flow Direction ◽  
Flow Speed ◽  
Experimental Results ◽  
Mushy Layer ◽  
Engineering Systems ◽  
Controlled Cooling ◽  
A Value ◽  
Constant Rate ◽  
Theoretical Predictions

The influence of an external shear flow on the evolution of a solidifying array of dendritic crystals, termed a mushy layer, is investigated through controlled cooling of an aqueous ammonium chloride solution in a laboratory flume. The controlled cooling produces a mushy layer that grows at a constant rate from the base of the flume over which a laminar shear flow is applied. We find a critical flow speed above which a spatiotemporal variation of the solid fraction of the layer appears with a planform transverse to the flow direction. The presence of this distinctive pattern of spanwise crevasses is compared with a simplified stability analysis in which the motion of the external fluid over the corrugated mush–liquid interface produces a pressure perturbation that drives flow and phase change within the mushy layer. This flow leads to a pattern of solidification and dissolution that is compared to the experimental results. The physical mechanism underlying the pattern formation is confirmed by the agreement between the theoretical predictions and experimental results. Finally, the comparison between theory and experiment provides a value for the mushy layer permeability, the evolution of which is of relevance to a host of geophysical, biological and engineering systems.

Lattice Boltzmann Simulations of Single Bubble Deformation and Breakup in a Shear Flow

2012 ◽  
Vol 4 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Yi. kun. Wei ◽  
Yuehong. Qian ◽  
Hui. Xu
Keyword(s):  
Shear Flow ◽  
Numerical Simulations ◽  
Lattice Boltzmann ◽  
Rotation Angle ◽  
Experimental Results ◽  
Single Bubble ◽  
Bubble Deformation ◽  
Lattice Boltzmann Simulations ◽  
Boltzmann Method ◽  
Theoretical Results

Lattice Boltzmann method (LBM) is used to simulate the deformation and breakup of single bubble in a shear flow. Numerical simulations of single bubble deformation are qualitatively compared with experimental results in a shear flow. Respectively the rotation angle θ is quantitatively compared with experimental results according to different capillary numbers ( Ca), which shows numerical simulations are in agreement with the experimental results and theoretical results. Finally, the breakup process of single bubble in a shear flow is simulated straightforwardly.

Axisymmetric propagating vortices in centrifugally stable Taylor–Couette flow

2013 ◽  
Vol 728 ◽  
pp. 458-470 ◽  
Author(s):  
C. Hoffmann ◽  
S. Altmeyer ◽  
M. Heise ◽  
J. Abshagen ◽  
G. Pfister
Keyword(s):  
Hopf Bifurcation ◽  
Shear Flow ◽  
Couette Flow ◽  
Instability Threshold ◽  
Experimental Results ◽  
Centrifugal Instability ◽  
Taylor Couette ◽  
Steady Vortices ◽  
Ekman Cells ◽  
Taylor Couette Flow

AbstractWe present numerical as well as experimental results of axisymmetric, axially propagating vortices appearing in counter-rotating Taylor–Couette flow below the centrifugal instability threshold of circular Couette flow without additional externally imposed forces. These propagating vortices are periodically generated by the shear flow near the Ekman cells that are induced by the non-rotating end walls. These axisymmetric vortices propagate into the bulk towards mid-height, where they get annihilated by rotating, non-propagating defects. These propagating structures appear via a supercritical Hopf bifurcation from axisymmetric, steady vortices, which have been discovered recently in centrifugally stable counter-rotating Taylor–Couette flow (Abshagen et al., Phys. Fluids, vol. 22, 2010, 021702). In the nonlinear regime of the Hopf bifurcation, contributions of non-axisymmetric modes also appear.

scholarly journals Rotation of a sphere in a viscoelastic liquid subjected to shear flow. Part II. Experimental results

2009 ◽  
Vol 53 (2) ◽  
pp. 459-480 ◽  
Author(s):  
Frank Snijkers ◽  
Gaetano D’Avino ◽  
Pier Luca Maffettone ◽  
Francesco Greco ◽  
Martien Hulsen ◽  
...  
Keyword(s):  
Shear Flow ◽  
Viscoelastic Liquid ◽  
Experimental Results ◽  
Flow Part

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

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