Search results for "Convection"

On the solution growth of single crystals of solid solutions

1986

Abstract Homogeneous solid solution crystals are needed for studying the behaviour of systems with a glass state or incommensurate phases. A simple solution growth procedure is described. It is based on a temperature difference growth method with thermally enforced convection and the use of equilibrated solid and liquid solutions. First results of its application to the [(CH3)4N]2ZnCl 4−xBrx and the Rb1−x(NH4)xH2PO4 systems are presented.

A numerical study of thermal conditions in the THM growth of HgTe

2002

A numerical simulation of the travelling heater method (THM) process in the growth of HgTe is carried out. The whole system (furnace, ampoule and charge) is taken into account in the frame of a quasi-steady-state model. The mass conservation condition for the solute in the liquid zone permits the determination of the rate of advance of the crystallisation isotherm as a function of the heater position. We claim to study the evolution of different magnitudes along the growth process, searching for the physical reasons which could be at the origin of defects in the form of thin layers observed in some growing experiences. To solve the governing equations of fluid flow, heat transfer and mass t…

Instabilités hydrodynamiques de fluides magnétiques en écoulements microfluidiques

2015

Advisors: Prof. Andrejs Cēbers (University of Latvia) & Prof. Régine Perzynski (University of Pierre and Marie Curie)

Natural Convection Heat Transfer in a Partially- or Completely-Partitioned Vertical Rectangular Enclosure

1991

Natural Convection in Liquid Metal-Filled Rectangular Enclosures with Volumetric Heating

1998

Magnetic characteristics of industrial dust from different sources of emission: A case study of Poland

2015

Abstract Dust emission and deposition in topsoil have negative effect on individual components of the ecosystem. In addition to routine geochemical analyses, magnetic measurements may provide useful complementary information related to the type, concentration and grain-size distribution of the technogenic magnetic particles (TMPs) and thus the degree of contamination of the environment. The aim of this contribution is to use magnetic parameters in distinguishing dust from a wide range of sources of air pollution (power industry, cement, coke, ceramic industries and biomass combustion). We measured magnetic susceptibility, hysteresis parameters and thermomagnetic curves. Our results suggest …

Influence of intracellular convection on the oxygen release by human erythrocytes

1972

There is general agreement today that intracellular diffusive transport of HbO2 and O2 limits the rate of oxygen uptake or release by the blood in the exchange vessels. Recent hemorheological results have shown that the mammalian erythrocyte exhibits fluidity as its most unique rheological property: it can be deformed continuously and rapidly, shear and normal stresses can be transmitted to the interior of the cell where systems of laminar flow are induced. These mechanical properties lead to the question whether or not intracellular convection does take place in the erythrocyte and to what extent it plays a part in gas exchange. A method was developed which subjects oxygen-saturated soluti…

Hotspot distribution, gravity, mantle tomography: evidence for plumes

1999

Abstract Thermal convection is the motor of Earth dynamics and therefore is the link between plate motions, hotspots, seismic velocity variations in the mantle, and anomalies of the gravity field. Small scale mantle anomalies, such as plumes, do, however, generally escape detection by tomographic methods. It is attempted to approach the problem of detection in a somewhat statistical manner. Correlations are sought between spherical harmonic expansions of the fields under study: the hotspot distribution, mantle velocity variations, gravity, heat flow. Using spherical harmonic representations of global fields implies integration and averaging over the whole globe. Thus, although relationships…

Formation of magnetoconvection by photoabsorptive methods in ferrofluid layers

2013

Abstract A periodic concentration grating was induced in a layer of ferrofluid by photoabsorption and thermophoresis under the action of the applied uniform magnetic field. The application of the external field causes the appearance of an internal demagnetizing field within the layer and of magnetic forces due to the non-uniform distribution of concentration. The induced magnetic forces cause the appearance of parasitic microconvection within the layer. The experimental observations of the formation stage of the grating are interpreted to explain magnetoconvection, making use of numerical simulations.

Effect of pseudo-gravitational acceleration on the dissolution rate of miscible drops

2017

The effect of pseudo-gravitational acceleration on the dissolution process of two phase miscible systems has been investigated at high acceleration values using a spinning drop tensiometer with three systems: 1-butanol/water, isobutyric acid/water, and triethylamine/water. We concluded that the dissolution process involves at least three different transport phenomena: diffusion, barodiffusion, and gravitational (buoyancy-driven) convection. The last two phenomena are significantly affected by the centrifugal acceleration acting at the interface between the two fluids, and the coupling with the geometry of the dissolving drop leads to a change of the mass flux during the course of the dissol…