Control of estuarine stratification and mixing by wind-induced straining of the estuarine density field

Estuaries ◽  
2005 ◽  
Vol 28 (3) ◽  
pp. 321-326 ◽  
Author(s):  
Malcolm E. Scully ◽  
Carl Friedrichs ◽  
John Brubaker
Keyword(s):  
Density Field ◽  
Estuarine Stratification

Aero-optics of subsonic turbulent boundary layers

2012 ◽  
Vol 696 ◽  
pp. 122-151 ◽  
Author(s):  
Kan Wang ◽  
Meng Wang
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Dominant Role ◽  
Elevation Angle ◽  
Turbulent Boundary Layers ◽  
Density Field ◽  
Small Scale ◽  
Number Range ◽  
Scale Turbulence

AbstractCompressible large-eddy simulations are carried out to study the aero-optical distortions caused by Mach 0.5 flat-plate turbulent boundary layers at Reynolds numbers of ${\mathit{Re}}_{\theta } = 875$, 1770 and 3550, based on momentum thickness. The fluctuations of refractive index are calculated from the density field, and wavefront distortions of an optical beam traversing the boundary layer are computed based on geometric optics. The effects of aperture size, small-scale turbulence, different flow regions and beam elevation angle are examined and the underlying flow physics is analysed. It is found that the level of optical distortion decreases with increasing Reynolds number within the Reynolds-number range considered. The contributions from the viscous sublayer and buffer layer are small, while the wake region plays a dominant role, followed by the logarithmic layer. By low-pass filtering the fluctuating density field, it is shown that small-scale turbulence is optically inactive. Consistent with previous experimental findings, the distortion magnitude is dependent on the propagation direction due to anisotropy of the boundary-layer vortical structures. Density correlations and length scales are analysed to understand the elevation-angle dependence and its relation to turbulence structures. The applicability of Sutton’s linking equation to boundary-layer flows is examined, and excellent agreement between linking equation predictions and directly integrated distortions is obtained when the density length scale is appropriately defined.

Development of CNT paste for high-current density field emitters

2010 ◽  
Author(s):  
Jae-Woo Kim ◽  
Jun-Tae Kang ◽  
Jin-Woo Jeong ◽  
Yoon-Ho Song
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Density Field ◽  
High Current ◽  
Field Emitters

Benthic foraminiferal δ18O in the ocean's temperature-salinity-density field: Constraints on Ice Age thermohaline circulation

1991 ◽  
Vol 6 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Rainer Zahn ◽  
Alan C. Mix
Keyword(s):  
Thermohaline Circulation ◽  
Density Field ◽  
Ice Age

Balanced Ocean-Data Assimilation near the Equator

2002 ◽  
Vol 32 (9) ◽  
pp. 2509-2519 ◽  
Author(s):  
Gerrit Burgers ◽  
Magdalena A. Balmaseda ◽  
Femke C. Vossepoel ◽  
Geert Jan van Oldenborgh ◽  
Peter Jan van Leeuwen
Keyword(s):  
Data Assimilation ◽  
Shallow Water ◽  
General Circulation ◽  
General Circulation Models ◽  
Density Field ◽  
Water Model ◽  
Optimal Interpolation ◽  
Shallow Water Model ◽  
Ocean Data Assimilation ◽  
Zonal Velocity

Abstract The question is addressed whether using unbalanced updates in ocean-data assimilation schemes for seasonal forecasting systems can result in a relatively poor simulation of zonal currents. An assimilation scheme, where temperature observations are used for updating only the density field, is compared to a scheme where updates of density field and zonal velocities are related by geostrophic balance. This is done for an equatorial linear shallow-water model. It is found that equatorial zonal velocities can be detoriated if velocity is not updated in the assimilation procedure. Adding balanced updates to the zonal velocity is shown to be a simple remedy for the shallow-water model. Next, optimal interpolation (OI) schemes with balanced updates of the zonal velocity are implemented in two ocean general circulation models. First tests indicate a beneficial impact on equatorial upper-ocean zonal currents.

scholarly journals Solar acoustic oscillations in a random density field

2003 ◽  
Vol 407 (2) ◽  
pp. 759-759
Author(s):  
L. Nocera ◽  
M. Mędrek ◽  
K. Murawski
Keyword(s):  
Density Field ◽  
Acoustic Oscillations

scholarly journals Aspects of renormalization in finite-density field theory

2015 ◽  
Vol 91 (19) ◽  
Author(s):  
A. Liam Fitzpatrick ◽  
Gonzalo Torroba ◽  
Huajia Wang
Keyword(s):  
Field Theory ◽  
Density Field ◽  
Finite Density

scholarly journals Non-Gaussian inference from non-linear and non-Poisson biased distributed data

2014 ◽  
Vol 10 (S306) ◽  
pp. 258-261
Author(s):  
Metin Ata ◽  
Francisco-Shu Kitaura ◽  
Volker Müller
Keyword(s):  
Dark Matter ◽  
Statistical Inference ◽  
Computer Code ◽  
Matter Density ◽  
Density Field ◽  
Distributed Data ◽  
Dark Matter Density ◽  
Posterior Sampling ◽  
Non Linear ◽  
Non Gaussian

AbstractWe study the statistical inference of the cosmological dark matter density field from non-Gaussian, non-linear and non-Poisson biased distributed tracers. We have implemented a Bayesian posterior sampling computer-code solving this problem and tested it with mock data based onN-body simulations.

scholarly journals Constraining primordial non-Gaussianity with moments of the large-scale density field

2014 ◽  
Vol 443 (2) ◽  
pp. 1402-1415 ◽  
Author(s):  
Qingqing Mao ◽  
Andreas A. Berlind ◽  
Cameron K. McBride ◽  
Robert J. Scherrer ◽  
Román Scoccimarro ◽  
...  
Keyword(s):  
Large Scale ◽  
Density Field

Density field of directed free-molecular flow from an annulus.

1969 ◽  
Vol 6 (6) ◽  
pp. 755-757 ◽  
Author(s):  
JOHN W. BROOK
Keyword(s):  
Density Field ◽  
Molecular Flow ◽  
Free Molecular Flow

Why Non-Uniform Density Suppresses the Precessing Vortex Core

2013 ◽  
Author(s):  
Kilian Oberleithner ◽  
Steffen Terhaar ◽  
Lothar Rukes ◽  
Christian Oliver Paschereit
Keyword(s):  
Natural Gas ◽  
Vortex Core ◽  
Hydrodynamic Instability ◽  
Density Field ◽  
Density Stratification ◽  
Reacting Flow ◽  
Global Instability ◽  
Global Mode ◽  
Precessing Vortex Core ◽  
Flow Oscillations

Isothermal swirling jets undergoing vortex breakdown are known to be susceptible to self-excited flow oscillations. They manifest in a precessing vortex core and synchronized growth of large-scale vortical structures. Recent theoretical studies associate these dynamics with the onset of a global hydrodynamic instability mode. These global modes also emerge in reacting flows, thereby crucially affecting the mixing characteristics and the flame dynamics. It is, however, observed that these self-excited flow oscillations are often suppressed in the reacting flow, while they are clearly present at isothermal conditions. This study provides strong evidence that the suppression of the precessing vortex core is caused by density stratification created by the flame. This mechanism is revealed by considering two reacting flow configurations: The first configuration represents a detached steam-diluted natural gas swirl-stabilized flame featuring a strong precessing vortex core. The second represents a natural gas swirl-stabilized flame anchoring near the combustor inlet, which does not exhibit self-excited oscillations. Experiments are conducted in a generic combustor test rig and the flow dynamics are captured using PIV and LDA. The corresponding density fields are approximated from the seeding density using a quantitative light sheet technique. The experimental results are compared to the global instability properties derived from hydrodynamic linear stability theory. Excellent agreement between the theoretically derived global mode frequency and measured precession frequency provide sufficient evidence to conclude that the self-excited oscillations are, indeed, driven by a global hydrodynamic instability. The effect of the density field on the global instability is studied explicitly by performing the analysis with and without density stratification. It turns out that the significant change on instability is caused by the radial density gradients in the inner recirculation zone and not by the change of the mean velocity field. The present work provides a theoretical framework to analyze the global hydrodynamic instability of realistic combustion configurations. It allows relating the flame position and the resulting density field to the emergence of a precessing vortex core.

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