Experimental Study of a Laminar Jet in a Double-Diffusion Environment

1995 ◽  
Vol 117 (3) ◽  
pp. 347-354 ◽  
Author(s):  
M. Priven ◽  
G. A. Bemporad ◽  
J. Atkinson ◽  
H. Rubin
Keyword(s):  
Fluid Layer ◽  
Double Diffusion ◽  
Vertical Displacement ◽  
Laminar Jet ◽  
Density Distributions ◽  
Fluid Layers ◽  
Laboratory Flume ◽  
Basic Features ◽  
Negatively Buoyant ◽  
Good Agreement

An experimental analysis of the flow development caused by the simultaneous injection and withdrawal of a buoyant fluid layer with low Reynolds number in a double-diffusion environment is presented. The injection of positively, neutrally, and negatively buoyant fluid layers was simulated in the experimental setup. Innovative procedures were developed to efficiently create the desired density distributions in the laboratory flume. Results presented in this paper concern the injection of fluid into environments stratified by temperature, salinity or both. Basic features of the flow patterns are described, in particular, intrusion rate, effect on ambient stratification and vertical displacement. The experimental data on the fluid vertical displacement were compared with results from a numerical model and good agreement was found.

Theoretical Study of a Laminar Jet in a Double-Diffusion Environment

1995 ◽  
Vol 117 (3) ◽  
pp. 341-346 ◽  
Author(s):  
M. Priven ◽  
J. F. Atkinson ◽  
G. A. Bemporad ◽  
H. Rubin
Keyword(s):  
Theoretical Study ◽  
Double Diffusion ◽  
Two Dimensional ◽  
Local Reference Frame ◽  
Field Development ◽  
Laminar Jet ◽  
Fluid Layers ◽  
Diffusion Effects ◽  
Local Reference ◽  
Layer Development

The flow field development associated with the injection of negatively, neutrally, and positively buoyant fluid layers into a stratified environment was analyzed in this study. The analysis considered two-dimensional (horizontal slot) fluid injection under laminar conditions in either temperature-stratified, salinity-stratified or double-diffusive stratified environments. The major features characterizing the buoyant layer development were identified. A numerical model, which integrates in a local reference frame the equations governing mass, momentum, heat and salinity fluxes, was developed. The model was used to examine the characteristic flow patterns for the two-dimensional buoyant discharges of interest in this study. It was also possible to show that double-diffusion effects may significantly influence the development of initially neutral fluid layers and cause a certain vertical deviation.

Plane turbulent jets in a bounded fluid layer

1992 ◽  
Vol 241 ◽  
pp. 587-614 ◽  
Author(s):  
T. Dracos ◽  
M. Giger ◽  
G. H. Jirka
Keyword(s):  
Experimental Investigation ◽  
Cross Section ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Two Dimensional ◽  
Vortical Structures ◽  
Secondary Currents ◽  
Fluid Layers ◽  
Bounding Surfaces

An experimental investigation of plane turbulent jets in bounded fluid layers is presented. The development of the jet is regular up to a distance from the orifice of approximately twice the depth of the fluid layer. From there on to a distance of about ten times the depth, the flow is dominated by secondary currents. The velocity distribution over a cross-section of the jet becomes three-dimensional and the jet undergoes a constriction in the midplane and a widening near the bounding surfaces. Beyond a distance of approximately ten times the depth of the bounded fluid layer the secondary currents disappear and the jet starts to meander around its centreplane. Large vortical structures develop with axes perpendicular to the bounding surfaces of the fluid layer. With increasing distance the size of these structures increases by pairing. These features of the jet are associated with the development of quasi two-dimensional turbulence. It is shown that the secondary currents and the meandering do not significantly affect the spreading of the jet. The quasi-two-dimensional turbulence, however, developing in the meandering jet, significantly influences the mixing of entrained fluid.

The application of the Whitehead theory of relativity to non-static, spherically symmetrical systems

1954 ◽  
Vol 222 (1151) ◽  
pp. 509-526 ◽  
Keyword(s):  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Current Standard ◽  
World Model ◽  
Basic Principles ◽  
Density Distributions ◽  
Free Particles ◽  
Static Systems ◽  
Solar Field ◽  
Good Agreement

In a recent paper Synge (1952) reformulated in current standard notation the basic principles of the theory of relativity of A. N. Whitehead and investigated the gravitational properties of a spherically symmetrical static distribution of matter. He applied this theory to the solar field and verified the result previously indicated by Whitehead (1922) that the theory is in good agreement with the local tests satisfied by Einstein’s general theory of relativity. The present paper extends the theory of Whitehead to non-static systems whose velocity and density distributions possess complete spherical symmetry about a spatial origin in a Galilean frame of reference. In particular, a uniformly expanding homogeneous world-model is constructed which differs significantly both from Milne’s model and that of special relativity. The motion of free particles and photons in this model is investigated and a formula for the law of red-shifts is derived.

Modelling double diffusion in soils and materials

2018 ◽  
Vol 27 (5-6) ◽  
Author(s):  
Ariadne-Αnne Tsambali ◽  
Avraam A. Konstantinidis ◽  
Elias C. Aifantis
Keyword(s):  
Double Diffusion ◽  
Chloride Diffusion ◽  
Theoretical Predictions ◽  
Sandy Aquifers ◽  
Good Agreement

AbstractThe double diffusivity model proposed earlier by Aifantis and co-workers was applied in this work for modelling the diffusion of metals in sandy aquifers, as well as chloride diffusion in concrete specimens. The theoretical predictions are in very good agreement with the measured concentrations in all cases, showing that the model is capable of dealing with a large variety of double diffusivity problems.

Experimental Study on the Recirculation of Homogeneous and Stratified Fluid Layers in the Advanced Solar Pond

1994 ◽  
Vol 116 (2) ◽  
pp. 74-78 ◽  
Author(s):  
Y. Keren ◽  
H. Rubin ◽  
G. A. Bemporad
Keyword(s):  
Double Diffusion ◽  
Stratified Fluid ◽  
Experimental Investigations ◽  
Laboratory Setup ◽  
Solar Pond ◽  
Fluid Layers ◽  
Data Density ◽  
And Control ◽  
Stable Flow ◽  
Transient And Steady State

The practical possibilities of constructing and operating a stable flow of homogeneous and stratified fluid layers in a solar pond were investigated in this study. A laboratory setup was prepared to carry out the experimental investigations. Transient and steady-state conditions were analyzed. A numerical model was developed to simulate heat, salt, and momentum transfer in the water body. The model was calibrated with the experimental data. Density and temperature measurements along the laboratory setup showed the configuration to be stable in all of the conditions which were analyzed. These experimental results indicated that through a proper multiselective injection and withdrawal procedure it was possible to create and control the double-diffusion stratified fluid layers, which characterizes the advanced solar pond.

scholarly journals Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO<sub>2</sub>(<i>ν</i><sub>3</sub>) and OH(<i>ν</i>) emission models

2017 ◽  
Vol 17 (16) ◽  
pp. 9751-9760 ◽  
Author(s):  
Peter A. Panka ◽  
Alexander A. Kutepov ◽  
Konstantinos S. Kalogerakis ◽  
Diego Janches ◽  
James M. Russell ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Vibrational Energy ◽  
Lower Thermosphere ◽  
Vibrational Energy Relaxation ◽  
Density Distributions ◽  
Direct Mechanism ◽  
Vibrational Levels ◽  
Emission Models ◽  
The Impact ◽  
Good Agreement

Abstract. In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν) in the nighttime mesosphere to the CO2(ν3) vibration, OH(ν) ⇒ N2(ν) ⇒ CO2(ν3), was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8–3 N2(1) molecules instead of one N2(1) molecule in each quenching reaction of OH(ν) + N2(0). Recently a new "indirect" channel of the OH(ν) energy transfer to N2(ν) vibrations, OH(ν) ⇒ O(1D) ⇒ N2(ν), was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9) + O(3P) was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO2(ν3) and OH(ν) vibrational level populations and emissions. We also compared our calculations with (a) the SABER/TIMED nighttime 4.3 µm CO2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere–lower thermosphere (MLT) and (b) with ground- and space-based observations of OH(ν) densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν) density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν) energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new  indirect  mechanism efficiently removes at least five quanta in each OH(ν ≥ 5) + O(3P) collision and provides the OH(ν) distributions which agree with both SABER limb OH emission observations and ground- and space-based OH(ν) density measurements. This analysis suggests that the important mechanism of the OH(ν) vibrational energy relaxation in the nighttime MLT, which was missing in the emission models of this atmospheric layer, has been finally identified.

scholarly journals Deformation prediction analysis of vertical displacement of deep foundation pit based on LIBSVM

2020 ◽  
Vol 206 ◽  
pp. 01021
Author(s):  
Yueyao Zhao ◽  
Jiawei Zhang ◽  
Haojie Li
Keyword(s):  
Support Vector Machine Model ◽  
Hot Spot ◽  
Vertical Displacement ◽  
Support Vector ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Machine Model ◽  
Deformation Prediction ◽  
Deep Foundation Pit ◽  
Good Agreement

The reliable prediction of the surface vertical displacement deformation of deep foundation pits is of great significance to the excavation of large foundation pits. The support vector machine model (LIBSVM) has become a hot spot in the prediction of deep foundation pit deformation and provides a new prediction for the deformation of deep foundation pits. In this paper, taking the deep foundation pit of Daoxianghu Road Station in xx as an example, a prediction model of vertical displacement on the ground is established based on LIBSVM and analysis shows that the prediction results based on the model are in good agreement with the measured data, and the MSE reaches 0.0323. The model is effective and has an effective prospective skill.

scholarly journals The Nuclear Structure for Exotic Neutron-Rich of 42, 43, 45,47K Nuclei

2016 ◽  
Vol 13 (1) ◽  
pp. 146-154
Author(s):  
Baghdad Science Journal
Keyword(s):  
Magnetic Dipole ◽  
Electron Scattering ◽  
Dipole Moments ◽  
Exotic Nucleus ◽  
Form Factors ◽  
Model Space ◽  
Density Distributions ◽  
Plane Wave Born Approximation ◽  
Magnetic Electron ◽  
Good Agreement

In this paper the proton, neutron and matter density distributions and the corresponding root mean square (rms) radii of the ground states and the elastic magnetic electron scattering form factors and the magnetic dipole moments have been calculated for exotic nucleus of potassium isotopes K (A= 42, 43, 45, 47) based on the shell model using effective W0 interaction. The single-particle wave functions of harmonic-oscillator (HO) potential are used with the oscillator parameters b. According to this interaction, the valence nucleons are asummed to move in the d3f7 model space. The elastic magnetic electron scattering of the exotic nuclei 42K (J?T= 2- 2), 43K(J?T=3/2+ 5/2), 45K (J?T= 3/2+ 7/2) and 47K (J?T= 1/2+ 9/2) investigated through Plane Wave Born Approximation (PWBA). The inclusion of core polarization effect through the effective g-factors is adequate to obtain a good agreement between the predicted and the measured magnetic dipole moments.

Microscopic spin-orbit potential for p +6He elastic scattering

2019 ◽  
Vol 28 (09) ◽  
pp. 1950074
Author(s):  
Zakaria M. M. Mahmoud ◽  
Awad A. Ibraheem ◽  
M. A. Hassanain
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Optical Model ◽  
Spin Orbit ◽  
Current Form ◽  
Density Distributions ◽  
Orbit Potential ◽  
Scattering Cross Sections ◽  
Good Agreement

In this work, we simultaneously reanalyzed the differential elastic scattering cross-sections ([Formula: see text]) and the vector analyzing power ([Formula: see text]) of [Formula: see text]He elastic scattering. This analysis was performed using the folded optical model for both real central and spin-orbit (SO) potentials, respectively. For the imaginary central, we used the usual Woods-Saxon (WS) form. Three different model density distributions are used to calculate the potential. We aimed to examine the applicability of the microscopically derived SO potential and the structure effect of 6He nucleus. The presence of the [Formula: see text] experimental data of [Formula: see text]He makes it interesting for this study. Our calculations showed that the three densities gave similar predictions for the cross-sections data. The three microscopic SO potentials calculations of [Formula: see text] are not in a good agreement with the experimental data. We concluded that the SO formalism in its current form needs more investigations for exotic halo nuclei.

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