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 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 III-1　Dynamics of Confined Water Phase Transition of Supercooled Water

RADIOISOTOPES ◽  
2014 ◽  
Vol 63 (6) ◽  
pp. 331-342
Author(s):  
Toshio YAMAGUCHI ◽  
Koji YOSHIDA
Keyword(s):  
Phase Transition ◽  
Supercooled Water ◽  
Water Phase ◽  
Confined Water

Spatio-Temporal Pattern Formation in Holling–Tanner Type Model with Nonlocal Consumption of Resources

2019 ◽  
Vol 29 (01) ◽  
pp. 1930002 ◽  
Author(s):  
Swadesh Pal ◽  
Malay Banerjee ◽  
S. Ghorai
Keyword(s):  
Wave Front ◽  
Traveling Wave ◽  
Traveling Wave Solution ◽  
Nonlocal Interaction ◽  
Nonlocal Term ◽  
Generalist Predator ◽  
Nonlocal Model ◽  
Traveling Wave Front ◽  
Temporal Models ◽  
Spatio Temporal

A wide variety of spatio-temporal models are available in literature which are unable to generate stationary patterns through Turing bifurcation. Introduction of nonlocal terms to the same model can produce Turing patterns and this is true even for a single species population model. In this paper, we consider a prey–predator model of Holling–Tanner type with a generalist predator and a nonlocal interaction in the intra-specific competition term of the prey population. Nonmonotonic functional response is assumed to describe consumption rate of the prey by the predator. The Turing instability condition has been studied for the model without the nonlocal term around coexisting steady states. We also determine the Turing domain in the presence of nonlocal interaction term. The spatial-Hopf bifurcation has been studied and it plays an important role to find the pure Turing domain for the nonlocal model. Furthermore, in the presence of nonlocal interaction, the nonlocal model produces traveling wave solution. Using linear stability analysis, we have obtained the wave speed for the traveling wave front analytically. With the help of numerical simulation, we have verified that the speed of the traveling wave front for the complete nonlinear nonlocal model matches with the analytical approximation. The emergence of wave trains has also been established for higher range of nonlocal interaction.

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

Developmental changes in flow-wave propagation velocity in embryonic chick vascular system

1997 ◽  
Vol 273 (3) ◽  
pp. H1523-H1529 ◽  
Author(s):  
M. Yoshigi ◽  
J. M. Ettel ◽  
B. B. Keller
Keyword(s):  
Wave Propagation ◽  
Phase Velocity ◽  
Wave Front ◽  
Blood Volume ◽  
Propagation Velocity ◽  
Vascular System ◽  
Front Velocity ◽  
Developmental Changes ◽  
Wave Propagation Velocity ◽  
Circulating Blood Volume

We analyzed flow-wave propagation velocity in the early embryonic vascular system and its responses to acute alterations in circulating blood volume. Two 20-MHz pulsed Doppler velocimeters were positioned along the arterial system in stage 18 (n = 12), 21 (n = 10), and 24 (n = 11) chick embryos. Distance between the two measurement sites was measured by video-microscopy. Phase velocity was calculated using Fourier transform up to the fourth harmonics. Wave-front velocity was also calculated by threshold technique. In a subset of embryos at stage 24 (n = 10), circulating blood volume was acutely altered to change stroke volume. Mean phase velocity increased from 42.9 +/- 3.3 to 95.8 +/- 7.5 cm/s from stage 18 to 24 (P < 0.05 by analysis of variance), whereas wave-front velocity increased from 52.8 +/- 2.4 to 72.2 +/- 5.2 cm/s. Stroke volume and mean aortic pressure paralleled the changes in mean phase velocity and wave-front velocity in normal development and in response to changes in circulating blood volume. Thus developmental changes in wave-propagation velocity were consistent with changes in the size of the vascular system, pressure range, and elastic properties of the arterial wall during systemic vasculogenesis in the embryo.

scholarly journals Anti-plane shear waves in periodic elastic composites: band structure and anomalous wave refraction

2015 ◽  
Vol 471 (2180) ◽  
pp. 20150152 ◽  
Author(s):  
Sia Nemat-Nasser
Keyword(s):  
Band Structure ◽  
Phase Velocity ◽  
Negative Refraction ◽  
Mass Density ◽  
Shear Waves ◽  
Variable Mass ◽  
Three Dimensional ◽  
Positive Energy ◽  
Plane Shear ◽  
Elastic Composites

For anti-plane shear waves in periodic elastic composites, it is shown that negative energy refraction can be accompanied by positive phase-velocity refraction and positive energy refraction can be accompanied by negative phase-velocity refraction , and that this can happen over a broad range of frequencies. Hence, in general, negative refraction does not necessarily require antiparallel group and phase-velocity vectors. Details are given for layered composites and the results are extended to, and illustrated for, two-dimensional periodic composites, revealing a wealth of information about the refractive characteristics of this class of composites. The composite's unit cell may consist of any number of constituents of any variable mass density and elastic modulus, admitting large discontinuities . A powerful variational-based solution method is used that applies to one-, two- and three-dimensional composites, irrespective of their constituents being homogeneous or heterogeneous. The calculations are direct, accurate and efficient, yielding the band structure, group-velocity, energy-flux and phase-velocity vectors as functions of the frequency and wavevector components, over an entire frequency band.

A Method for Measuring Interdiffusion Coefficients in Liquids by Wave-front-shearing Interferometry

1975 ◽  
Vol 30 (1) ◽  
pp. 35-37 ◽  
Author(s):  
Silas E. Gustafsson ◽  
Ernest Karawacki ◽  
Isao Okada
Keyword(s):  
Diffusion Process ◽  
Wave Front ◽  
Concentration Distribution ◽  
Optic Axis ◽  
New Method ◽  
Shearing Interferometry ◽  
Flat Surfaces ◽  
Fused Quartz ◽  
Interdiffusion Coefficients

Abstract A new method for measuring interdiffusion coefficients in transparent liquids is presented. By using a diffusion vessel made of fused quartz with optically flat surfaces perpendicular to the optic axis it is possible to follow the complete concentration distribution with a wave-front-shearing interferometer during the diffusion process.

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