Liquid/liquid displacement in a vibrating capillary.

Mechanical vibrations can alter static and dynamic distributions of fluids in porous matrices. A popular theory that explains non-destructive changes in fluids percolation induced by vibrations involves elasticity of a solid matrix and compressibility of fluids. Owing to strong damping, elastic and acoustic deformations always remain bounded to narrow zones (a few centimetres) near the source of vibrations.

Dynamics of a bubble in oscillating viscous liquid.

This article is devoted to the investigation of gaseous bubble dynamics in oscillating viscous liquids of different density values. The study is conducted numerically using the level-set method with a non-stationary approach. The bubble is initially located near the upper wall of the container.

Experimental study of temporal dynamics of cavitation bubbles selectively attached to the solid surfaces of different hydrophobicity under the action of ultrasound.

In this work, we experimentally investigated the dynamics of vapor-gas bubbles arising in distilled water under the action of ultrasound (US), near and on the surface of solid plates with various surface properties. In the experiments, we used the plates made of Teflon, acrylic glass, and amorphous quartz, with various hydrophobic properties (contact angle). The experiments showed a significant effect of surface properties on the dynamics of bubbles oscillating near and on a solid surface under the influence of ultrasound.

A ternary mixture at the border of Soret separation stability.

Ternary mixtures with the Soret effect are prone to triple-diffusive convection in a thermal field. The Soret coefficients of the toluene-methanol-cyclohexane mixture, measured in microgravity at a given composition [0.62-0.

Nonequilibrium Capillary Pressure of a Miscible Meniscus.

We examine the dynamics of a miscible displacement in a capillary, calculating the nonequilibrium capillary pressure of a moving (and slowly diffusing) miscible meniscus. During the displacement, the capillary pressure varies with time following stretching and smearing of a miscible interface. The capillary pressure remains different from zero for a long time (on a diffusion time scale), slowing the displacement.

Magnetic Circular Dichroism of -Phenyl-Substituted Pd-Octaethylporphyrins.

Absorption and magnetic circular dichroism (MCD) spectra have been measured and theoretically simulated for a series of palladium octaethylporphyrins substituted at the positions with phenyl groups ( = 0-4). Analysis of the spectra included the perimeter model and time-dependent density functional theory (TDDFT) calculations. With the increasing number of phenyl substituents, the molecule is transformed from a positive hard (ΔHOMO > ΔLUMO) to a soft (ΔHOMO ≈ ΔLUMO) chromophore.

[Signs of proliferative process after laser treatment of advanced glaucoma].

Unlabelled: The universally established method for effective and less-invasive reduction of the intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG) is a two-step method consisting of non-penetrating deep sclerectomy (NDSE) followed by laser goniopuncture of the Descemet's membrane (Descemet's goniopuncture; DGP). However, the hypotensive effect can diminish at different times during the follow-up due to excessive scarring in surgically formed outflow tracts (SFOT).

Purpose: To evaluate the condition of SFOT in dynamics with Visante OCT after one-step combined laser technique consisting of modified selective laser activation of the trabecula (MSLAT) and DGP in advanced POAG patients with normalized IOP who have pronounced pigmentation of the trabecular meshwork and stage II pseudoexfoliation syndrome (PES).

Results of the DCMIX1 experiment on measurement of Soret coefficients in ternary mixtures of hydrocarbons under microgravity conditions on the ISS.

The Soret coefficients of a set of ternary systems of 1,2,3,4-tetrahydronaphthalene (THN), isobutylbenzene (IBB), and n-dodecane (nC) at 298.15 K were measured under microgravity condition aboard the International Space Station in the frame of the DCMIX1 experiment. The present work includes a comprehensive study of possible data processing sequences for the interpretation of interferometric Soret experiments in ternary systems.

Kelvin-Helmholtz and Holmboe instabilities of a diffusive interface between miscible phases.

The stability of a shear flow imposed along a diffusive interface that separates two miscible liquids (a heavier liquid lies underneath) is studied using direct numerical simulations. The phase-field approach is employed for description of a thermo- and hydrodynamic evolution of a heterogeneous binary mixture. The approach takes into account the dynamic interfacial stresses at a miscible interface and uses the extended Fick's law for setting the diffusion transport (the diffusion flux is proportional to the gradient of chemical potential).

European Space Agency experiments on thermodiffusion of fluid mixtures in space.

This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented.

Nonlinear regimes of Soret-driven convection of ternary fluid with fixed vertical heat flux at the boundaries.

Nonlinear regimes of the Soret-induced convection of a ternary mixture in a rectangular cavity with the vertical heat flux at the boundaries are studied numerically. Linear stability analysis performed earlier for a plane horizontal layer has shown that in a wide range of parameters the longwave instability is dominant. Nonlinear calculations performed in the present work for the parameter ranges where the monotonic longwave instability is dominant according to the linear stability analysis, show that at large supercriticalities the multi-vortex stationary flows could be realized.

Phase-field modeling of an immiscible liquid-liquid displacement in a capillary.

We develop a numerical model for a two-phase flow of a pair of immiscible liquids within a capillary tube. We assume that a capillary is initially saturated with one liquid and the other liquid is injected via one of the capillary's ends. The governing equations are solved in the velocity-pressure formulation, so the pressure levels are imposed at the capillary inlet and outlet ends.

Stability of a stationary plane-parallel flow of a ternary fluid between two vertical plates maintained at constant different temperatures.

The linear stability of a steady convective flow of a ternary mixture placed between differently heated vertical rigid plates is studied. The applied temperature gradient induces concentration gradients due to the Soret effect. The analysis is done for the case when separation ratios of ternary mixture, i.

Measurement of Soret coefficients in a ternary mixture of toluene-methanol-cyclohexane in convection-free environment.

We report on the measurement of Soret (S) coefficients in the ternary system toluene (T)-methanol (M)-cyclohexane (Ch) onboard the International Space Station in the experiment selectable optical diagnostic instrument/DCMIX (Diffusion Coefficients Measurement in ternary mIXtures). Nine experiments were conducted in the range of mean temperatures between 298.15 K and 306.

Stability of the fluid interface in a Hele-Shaw cell subjected to horizontal vibrations.

The stability of the horizontal interface of two immiscible viscous fluids in a Hele-Shaw cell subject to gravity and horizontal vibrations is studied. The problem is reduced to the generalized Hill equation, which is solved analytically by the multiple scale method and numerically. The long-wave instability, the resonance (parametric resonance) excitation of waves at finite frequencies of vibrations (for the first three resonances), and the limit of high-frequency vibrations are studied analytically under the assumption of small amplitudes of vibrations and small viscosity.

Phase-field modelling of gravity-capillary waves on a miscible interface.

Using the approach of direct numerical simulations we investigate the gravity-capillary waves induced on a horizontal interface between two slowly miscible liquids. It is assumed that the liquids are just brought into contact, and thus the interface is slowly smeared by the action of interfacial diffusion. It is also assumed that the initial shape of the interface is distorted by harmonic perturbations, which results in the development of the gravity-capillary surface waves.

Onset and non-linear regimes of Soret-induced convection in binary mixtures heated from above.

The paper deals with the investigation of the onset and non-linear regimes of convection of liquid binary mixtures with negative Soret effect heated from above. The linear stability of a convectionless state in a horizontal layer is studied by the numerical solution of the linearized problem on the temporal evolution of small perturbations of the unsteady base state. Non-linear regimes of convection are investigated by the numerical solution of the non-linear unsteady equations for a horizontally elongated rectangular cavity.

Phase diagram of a binary mixture in a closed cavity.

Normally, the phase diagram is reported as a property of the binary mixture. We show that the phase diagram (that is, the zones of thermodynamic stability of the states of the binary mixture) is also affected by the size of the container. We investigate the thermodynamic stability of the binary mixture in a closed cavity, and identify the zone in parameters where the binary mixture is heterogeneous in equilibrium (the zone of spinodal decomposition), the zone where the mixture is always homogeneous in equilibrium, and the zone where the transition between these two states is possible (the metastable nucleation zone).

Onset of Soret-induced convection in a horizontal layer of ternary fluid with fixed vertical heat flux at the boundaries.

The paper deals with the investigation of the onset and weakly nonlinear regimes of the Soret-driven convection of ternary liquid mixture in a horizontal layer with rigid impermeable boundaries subjected to the prescribed constant vertical heat flux. It is found that there are monotonous and oscillatory longwave instability modes. The boundary of the monotonous longwave instability in the parameter plane Rayleigh number Ra - net separation ratio [Formula: see text] at fixed separation ratio of one of solutes consists of two branches of hyperbolic type.

Instability of plane-parallel flow of incompressible liquid over a saturated porous medium.

The linear stability of plane-parallel flow of an incompressible viscous fluid over a saturated porous layer is studied to model the instability of water flow in a river over aquatic plants. The saturated porous layer is bounded from below by a rigid plate and the pure fluid layer has a free, undeformable upper boundary. A small inclination of the layers is imposed to simulate the riverbed slope.

Stability of uniform vertical flow through a close porous filter in the presence of solute immobilization.

In the present paper we consider slow filtration of a mixture through a close porous filter. The heavy solute penetrates slowly into the porous filter due to the external vertical filtration flow and diffusion. This process is accompanied by the formation of the domain with heavy fluid near the upper boundary of the filter.

Running interfacial waves in a two-layer fluid system subject to longitudinal vibrations.

We study the waves at the interface between two thin horizontal layers of immiscible fluids subject to high-frequency horizontal vibrations. Previously, the variational principle for energy functional, which can be adopted for treatment of quasistationary states of free interface in fluid dynamical systems subject to vibrations, revealed the existence of standing periodic waves and solitons in this system. However, this approach does not provide regular means for dealing with evolutionary problems: neither stability problems nor ones associated with propagating waves.

High-frequency vibration effect on the stability of a horizontal layer of ternary fluid.

The effect of small-amplitude high-frequency longitudinal vibrations on the stability of a horizontal layer of ternary fluid is studied in the framework of average approach. Long-wave instability is studied analytically and instability to the perturbations with finite wave numbers is studied numerically. It is found that, similar to the case when vibrations are absent, for ternary fluids there exist monotonic and oscillatory long-wave instability modes.