scholarly journals Rectified Diffusion of Gas Bubbles in Molten Metal during Ultrasonic Degassing

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 536
Author(s):  
Yuning Zhang ◽  
Yuning Zhang
Keyword(s):  
Analytical Solution ◽  
Molten Metal ◽  
Molten Aluminum ◽  
Present Model ◽  
Gas Bubbles ◽  
Ultrasonic Field ◽  
Hydrogen Bubbles ◽  
Diffusion Of Hydrogen ◽  
Diffusion Behaviors

In the present paper, an analytical solution of rectified diffusion of processes of gas bubbles in molten metal is derived for the purpose of predicting the diffusion behaviors of gas bubbles during ultrasonic degassing. In the present model, a theoretical threshold (in terms of the amplitude of the applied ultrasonic field) is determined for the evaluation of the ultrasonic degassing effects. The diffusion of hydrogen bubbles in molten aluminum is predicted, so as to provide examples to illustrate the important findings of the present work.

scholarly journals The effect of magnetic field on the dynamics of gas bubbles in water electrolysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yan-Hom Li ◽  
Yen-Ju Chen
Keyword(s):  
Magnetic Field ◽  
Swirling Flow ◽  
Gas Bubbles ◽  
Water Electrolysis ◽  
Platinum Electrodes ◽  
Optimal Layout ◽  
Parallel Magnetic Field ◽  
Hydrogen Bubbles ◽  
The Magnetic Field ◽  
Sluggish Flow

AbstractThis study determines the effect of the configuration of the magnetic field on the movement of gas bubbles that evolve from platinum electrodes. Oxygen and hydrogen bubbles respectively evolve from the surface of the anode and cathode and behave differently in the presence of a magnetic field due to their paramagnetic and diamagnetic characteristics. A magnetic field perpendicular to the surface of the horizontal electrode causes the bubbles to revolve. Oxygen and hydrogen bubbles revolve in opposite directions to create a swirling flow and spread the bubbles between the electrodes, which increases conductivity and the effectiveness of electrolysis. For vertical electrodes under the influence of a parallel magnetic field, a horizontal Lorentz force effectively detaches the bubbles and increases the conductivity and the effectiveness of electrolysis. However, if the layout of the electrodes and magnetic field results in upward or downward Lorentz forces that counter the buoyancy force, a sluggish flow in the duct inhibits the movement of the bubbles and decreases the conductivity and the charging performance. The results in this study determine the optimal layout for an electrode and a magnetic field to increase the conductivity and the effectiveness of water electrolysis, which is applicable to various fields including energy conversion, biotechnology, and magnetohydrodynamic thruster used in seawater.

scholarly journals Wetting of carbon by molten aluminum under ultrasonic field

2021 ◽  
Vol 639 ◽  
pp. 012008
Author(s):  
J T Zhao ◽  
Z M Jiang ◽  
J W Zhu ◽  
S D Zhang ◽  
Y L Li
Keyword(s):  
Molten Aluminum ◽  
Ultrasonic Field

scholarly journals Effects of phase shift on bipartite and multipartite correlations of a spin chain under dephasing

Open Physics ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Ai-Xi Chen ◽  
Jian-Song Zhang
Keyword(s):  
Steady State ◽  
Phase Shift ◽  
Analytical Solution ◽  
Spin Chain ◽  
Quantum Discord ◽  
Present Model ◽  
Spin Squeezing ◽  
Heisenberg Chain ◽  
Initial Correlations ◽  
Long Time

AbstractWe investigate the effects of phase shift on entanglement, quantum discord, geometric discord, and spinsqueezing of a Heisenberg chain under dephasing. An analytical solution of the present model is obtained. Our results show that the initial correlations of the spin chain could be partially stored for a long time in the presence of dephasing and the amount of steady state correlations can be adjusted via phase shift. Particularly, we find the effects of phase shift on quantum discord and geometric discord are not always the same, i.e., the increase of geometric discord does not always imply the increase of quantum discord. Then, we calculate the spin-squeezing of the spin chain and find that spin-squeezing first increases with time and then reaches a plateau. The amount of spin-squeezing can be controlled via phase shift.

The Non-Stationary Dynamic Analytical Solution of a Spherical/Cylindrical Cavity Expansion

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
V. R. Feldgun ◽  
D. Z. Yankelevsky
Keyword(s):  
Analytical Solution ◽  
General Solution ◽  
Cylindrical Cavity ◽  
Constant Velocity ◽  
Present Model ◽  
Elastic Region ◽  
Cavity Expansion ◽  
Special Cases ◽  
Significant Difference ◽  
Cavity Boundary

Abstract A review of the pertinent literature related to the dynamic expansion of a spherical/cylindrical cavity shows that all the solutions with kinematic boundary conditions deal with a constant velocity at the cavity boundary. This paper develops a new general solution of the nonstationary dynamic problem of cavity expansion, which allows the application of time-dependent motion conditions at the cavity boundary. This solution can be used, for example, in the development of approximate approaches for projectiles penetrating with a non-constant velocity into different targets. Due to the complexity of the nonlinear nonstationary problem, an analytical solution of the problem may be developed if simplified constitutive relationships are used. In the present model, a simplified material model with a locked equation of state and a linear shear failure relationship is implemented. This solution may be applied to different materials such as concrete, soil, and rock. Special cases of the newly developed nonstationary solution are compared with different spherical and cylindrical cavity expansions solutions reported in the literature, and a good agreement is obtained. The capability of the present model is demonstrated in a following investigation of representative cases of cavity expansion with zero, constant, and variable acceleration of the cavity boundary. A significant difference in the stress variation for the different cases is shown. Along with the general solution which deals with an elastic–plastic region, a simplified solution which disregards the contribution of the elastic region is presented and the evaluation of the elastic region effect may be assessed.

scholarly journals Effects of Monovacancy and Divacancies on Hydrogen Solubility, Trapping and Diffusion Behaviors in fcc-Pd by First Principles

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4876
Author(s):  
Bao-Long Ma ◽  
Yi-Yuan Wu ◽  
Yan-Hui Guo ◽  
Wen Yin ◽  
Qin Zhan ◽  
...  
Keyword(s):  
First Principles ◽  
Vacancy Defect ◽  
First Principles Calculations ◽  
Vacancy Defects ◽  
Target Station ◽  
Hydrogen Bubbles ◽  
Radiation Resistant ◽  
Key Issues ◽  
And Diffusion ◽  
Diffusion Behaviors

The hydrogen blistering phenomenon is one of the key issues for the target station of the accelerator-based neutron source. In the present study, the effect of monovacancies and divacancies defects on the solution, clustering and diffusion behaviors of H impurity in fcc-Pd were studied through first principles calculations. Our calculations prove that vacancies behave as an effective sink for H impurities. We found that, although the H-trap efficiency of the larger vacancy defect was reduced, its H-trap ability strengthened. There is a short-ranged area around the vacancy defects in which H impurities tend to diffuse to vacancy defects, gather and form hydrogen bubbles. Therefore, the characteristic of large vacancy defects formation in materials should be considered when screening anti-blistering materials for neutron-producing targets or when designing radiation resistant composite materials.

A Theoretical Note on Mode I Crack Kinking and Branching

2010 ◽  
Vol 118-120 ◽  
pp. 314-318
Author(s):  
Y.J. Xie ◽  
Xiao Zhi Hu ◽  
X.H. Wang
Keyword(s):  
Analytical Solution ◽  
Release Rate ◽  
Crack Extension ◽  
Present Model ◽  
Crack Branching ◽  
Mode I ◽  
Mode I Crack ◽  
Static Mode ◽  
Crack Kinking ◽  
Branching Angle

An energy-based fracture mode has been derived for the mode I crack kinking and branching. The classic -integral has been further explored by a new partial integral path and the analytical solution of the energy release rate for crack kinking and branching from a mode-I crack tip has been established. The crack kinking/branching angle has also been analytically derived. It shows that the Griffith’s theorem and conservation law can be applied to both model I crack extension and model I crack kinking and branching. The branching mechanism for quasi-static mode-I crack has been theoretically investigated. The branching toughness and the K-based criterion for crack branching have been defined. The crack branching phenomena predicted by the present model are in well agreement with the experimental observations reported in the literatures.

A Model for Surface Induced Growth of Inert Gas Bubbles in Irradiated Copper-Boron Alloys

2006 ◽  
Author(s):  
G. P. Tiwari ◽  
E. Ramadasan
Keyword(s):  
Present Model ◽  
External Surface ◽  
Gas Bubbles ◽  
Lattice Diffusion ◽  
Inert Gas ◽  
Limited Extent ◽  
Direct Proportion ◽  
Helium Gas ◽  
The Matrix ◽  
Crystalline Matrix

A matrix containing inert gas bubbles dilates in direct proportion to the growth experienced by the gas bubbles. This phenomenon is termed as swelling. A model for the swelling induced by the growth of the helium gas bubbles in irradiated copper-boron alloys is presented. The bubbles grow by acquiring vacancies from the external surface, which acts as a source of vacancies. The vacancies reach the surface of the bubbles mainly via lattice diffusion and to a limited extent via diffusion through short-circuiting paths such as grain boundaries and dislocation pipes. The model predicts that overall swelling of the matrix varies as 1.5th power of time. Another consequence of the present model is that the growth rate of a gas bubble varies inversely as the cube of its distance from the external surface. The model has been applied to the data on irradiated copper-boron alloys and found to be in accord with the experimental results. The model is general and can be applied to the growth of all kinds of stationary inert gas bubbles trapped within a crystalline matrix.

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