scholarly journals Investigation of convective structures and phase transition induced by non-stationary boundary conditions in a horizontal layer of water

2019 ◽  
Author(s):  
Виталий Арбузов ◽  
Vitaliy Arbuzov ◽  
Эдуард Арбузов ◽  
Eduard Arbuzov ◽  
Владимир Бердников ◽  
...  
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Water Layer ◽  
Horizontal Layer ◽  
Temperature Fields ◽  
Special Importance ◽  
Stationary Boundary ◽  
Convective Structures ◽  
Numerical Simulation Methods ◽  
Lower Heat

The evolution of convective structures and the phase transition induced by non-stationary boundary conditions in a horizontal water layer bounded by flat heat-exchange surfaces were studied by shear interferometry and numerical simulation methods. Numerical modeling of the temperature field as a field of isotherms in the mode of monotonous cooling of horizontal walls was performed. The problem of fragmentary reconstruction of hilbertograms and shear interferograms images from a numerical model of the isotherm field was solved. The hydrodynamics of convective currents, the coevolution of temperature fields, interference and Hilbert structures have been modeled and studied taking into account the inversion of water density in the vicinity of the isotherm (+4°C), under conditions of phase transition and growth of the ice layer on the lower heat transfer plane. The simulation was performed using a proprietary software package. The relevance of this kind of research is due to the special importance of convection in geodynamics, physics of the atmosphere and the ocean, in hydrodynamic and thermophysical processes associated with the formation and growth of crystals.

scholarly journals Study of convective structures and phase transition induced in a water layer by non-stationary boundary conditions

2019 ◽  
Vol 1421 ◽  
pp. 012047
Author(s):  
Yu N Dubnishchev ◽  
V A Arbuzov ◽  
E V Arbuzov ◽  
V S Berdnikov ◽  
O S Zolotukhina ◽  
...  
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Water Layer ◽  
Stationary Boundary ◽  
Convective Structures

Optical diagnostics of convective structures induced by non-stationary boundary conditions in a vertical water layer

2018 ◽  
Vol 10 (4) ◽  
pp. 134-144 ◽  
Author(s):  
Yu.N. Dubnishchev ◽  
V.A. Arbuzov ◽  
E.V. Arbuzov ◽  
V.S. Berdnikov ◽  
S.A. Kislytsin ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Optical Diagnostics ◽  
Water Layer ◽  
Stationary Boundary ◽  
Convective Structures

scholarly journals Hilbert diagnostics of convective structures and phase transition in super cooled water

2018 ◽  
Vol 7 (2.23) ◽  
pp. 295
Author(s):  
Yu. N. Dubnishchev ◽  
V A. Arbuzov ◽  
E V. Arbuzov ◽  
V S. Berdnikov ◽  
O S. Melekhina ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Velocity ◽  
Wave Front ◽  
Supercooled Water ◽  
Horizontal Layer ◽  
Positive Energy ◽  
Flat Surfaces ◽  
Convective Structures ◽  
Spatio Temporal ◽  
Hilbert Optics

The evolution of the crystallization wave front and convective structures in a horizontal layer of supercooled water bounded by tempera- ture-controlled flat surfaces is visualized using methods of Hilbert optics. The phase transition is manifested by the occurrence of a crys- tallization wave and is accompanied by a positive energy release, which, in turn, affects the dynamic distribution of the optical phase density gradient in supercooled water and induces phase perturbations in the probing light field. The results of measurements of the phase velocity and the shape of the crystallization front approximated by Bezier curves are presented. The wave front velocity is obtained using modified time-of-fight method. The phase velocity field is found to exhibit spatio-temporal quasi-periodicity that can be related to the existence of oscillatory phenomena in the crystallization process. 

Optical Hilbert diagnostics of convective structures and phase transition in a horizontal layer of supercooled water

2017 ◽  
Vol 62 (10) ◽  
pp. 1599-1601
Author(s):  
V. A. Arbuzov ◽  
E. V. Arbuzov ◽  
V. S. Berdnikov ◽  
Yu. N. Dubnishchev ◽  
O. S. Melekhina
Keyword(s):  
Phase Transition ◽  
Supercooled Water ◽  
Horizontal Layer ◽  
Convective Structures

scholarly journals Holographic anisotropic model for light quarks with confinement-deconfinement phase transition

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Irina Ya. Aref’eva ◽  
Kristina Rannu ◽  
Pavel Slepov
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Chemical Potential ◽  
String Tension ◽  
Isotropic Case ◽  
Holographic Model ◽  
Anisotropic Model ◽  
Dilaton Field ◽  
Cornell Potential ◽  
Qcd Phase Diagram

Abstract We present a five-dimensional anisotropic holographic model for light quarks supported by Einstein-dilaton-two-Maxwell action. This model generalizing isotropic holographic model with light quarks is characterized by a Van der Waals-like phase transition between small and large black holes. We compare the location of the phase transition for Wilson loops with the positions of the phase transition related to the background instability and describe the QCD phase diagram in the thermodynamic plane — temperature T and chemical potential μ. The Cornell potential behavior in this anisotropic model is also studied. The asymptotics of the Cornell potential at large distances strongly depend on the parameter of anisotropy and orientation. There is also a nontrivial dependence of the Cornell potential on the boundary conditions of the dilaton field and parameter of anisotropy. With the help of the boundary conditions for the dilaton field one fits the results of the lattice calculations for the string tension as a function of temperature in isotropic case and then generalize to the anisotropic one.

Finite Element Simulation of Laser Beam Welding Induced Residual Stresses and Distortions in a T-Joint Configuration for Aeronautic Structures

2009 ◽  
Author(s):  
Muhammad Zain-ul-abdein ◽  
Daniel Ne´lias ◽  
Jean-Franc¸ois Jullien ◽  
Dominique Deloison
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Laser Beam ◽  
Boundary Conditions ◽  
Laser Beam Welding ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Small Scale ◽  
Joint Configuration ◽  
Simulation Results

Laser beam welding has found its application in the aircraft industry for the fabrication of fuselage panels in a T-joint configuration. However, the inconveniences like distortions and residual stresses are inevitable consequences of welding. The effort is made in this work to experimentally measure and numerically simulate the distortions induced by laser beam welding of a T-joint with industrially used thermal and mechanical boundary conditions on the thin sheets of aluminium 6056-T4. Several small scale experiments were carried out with various instrumentations to establish a database necessary to verify the simulation results. Finite element (FE) simulation is performed with Abaqus and the conical heat source is programmed in FORTRAN. Heat transfer analysis is performed to achieve the required weld pool geometry and temperature fields. Mechanical analysis is then performed with industrial loading and boundary conditions so as to predict the distortion and the residual stress pattern. A good agreement is found amongst the experimental and simulation results.

Thermal phase transition behaviours of the blue phase of bent-core nematogen and chiral dopant mixtures under different boundary conditions

Soft Matter ◽  
2014 ◽  
Vol 10 (41) ◽  
pp. 8224-8228 ◽  
Author(s):  
Min-Jun Gim ◽  
Gohyun Han ◽  
Suk-Won Choi ◽  
Dong Ki Yoon
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Liquid Crystalline ◽  
Isotropic Phase ◽  
Different Boundary Conditions ◽  
Various Boundary Conditions ◽  
Thermal Phase Transition ◽  
Thermal Phase ◽  
Blue Phase ◽  
Chiral Dopants

We have investigated dramatic changes in the thermal phase transition of a liquid-crystalline (LC) blue phase (BP) consisting of bent-core nematogen and chiral dopants under various boundary conditions during cooling from the isotropic phase.

Thermo-Solutal Convection of a Nanofluid Utilizing Fourier’s-Type Compass Conditions

2020 ◽  
Vol 9 (4) ◽  
pp. 362-374
Author(s):  
J. C. Umavathi ◽  
Ali J. Chamkha
Keyword(s):  
Brownian Motion ◽  
Prandtl Number ◽  
Boundary Conditions ◽  
Volume Fraction ◽  
Temperature Fields ◽  
Physical Parameters ◽  
Surface Boundary ◽  
Perturbation Scheme ◽  
Runge Kutta ◽  
The Impact

Nanotechnology has infiltrated into duct design in parallel with many other fields of mechanical, medical and energy engineering. Motivated by the excellent potential of nanofluids, a subset of materials engineered at the nanoscale, in the present work, a new mathematical model is developed for natural convection in a vertical duct containing nanofluid. Numerical scrutiny for the double-diffusive free and forced convection within a duct encumbered with nanofluid is performed. Buongiorno’s model is deployed to define the nanofluid. Robin boundary conditions are used to define the surface boundary conditions. Thermal and concentration equations envisage the viscous, Brownian motion, thermosphores of the nanofluid, Soret and Dufour effects. Using the Boussi-nesq approximation the solutal buoyancy effect as a result of gradients in concentration are incorporated. The conservation equations which are nonlinear are numerically estimated using fourth order Runge-Kutta methodology and analytically ratifying regular perturbation scheme. The mass, heat, nanoparticle concentration and species concentration fields on eight dimensionless physical parameters such as thermal and mass Grashof numbers, Brownian motion parameter, thermal parameter, Prandtl number, Eckert number, Schmidt parameter, and Soret parameter are calculated. The impact of these parameters are outlined pictorially. The velocity and temperature fields are boosted with the thermal Grashof number. The Soret and the Schemidt parameters reduces the nanoparticle volume fraction but it heightens the momentum, temperature and concentration. At the cold wall thermal and concentration Grashof numbers reduces the Nusselt values but they increase the Nusselt values at the hot wall. The reversal consequence was attained at the hot plate. The perturbation and Runge-Kutta solutions are equal in the nonappearance of Prandtl number. The (E. Zanchini, Int. J. Heat Mass Transfer 41, 3949 (1998)). results are restored for the regular fluid. The heat transfer rate is high for nanofluid when matched with regular fluid.

scholarly journals Evidence of the Poisson/Gaudin–Mehta phase transition for band matrices on global scales

2018 ◽  
Vol 07 (02) ◽  
pp. 1850002
Author(s):  
Sheehan Olver ◽  
Andrew Swan
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Rate Of Convergence ◽  
Critical Behavior ◽  
Level Density ◽  
Boundary Effects ◽  
Fourth Moment ◽  
Band Matrices ◽  
Band Matrix ◽  
Symmetric Band

We prove that the Poisson/Gaudin–Mehta phase transition conjectured to occur when the bandwidth of an [Formula: see text] symmetric band matrix grows like [Formula: see text] is naturally observable in the rate of convergence of the level density to the Wigner semi-circle law. Specifically, we show for periodic and non-periodic band matrices the rate of convergence of the fourth moment of the level density is independent of the boundary conditions in the localized regime [Formula: see text] with a rate of [Formula: see text] for both cases, whereas in the delocalized regime [Formula: see text] where boundary effects become important, the rate of convergence for the two ensembles differs significantly, slowing to [Formula: see text] for non-periodic band matrices. Additionally, we examine the case of thick non-periodic band matrices [Formula: see text], showing that the fourth moment is maximally deviated from the Wigner semi-circle law when [Formula: see text], and provide numerical evidence that the eigenvector statistics also exhibit critical behavior at this point.

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