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In order to investigate the influence of liquid viscosity and surface roughness of the substrate on the improvement of wettability by ultrasonic vibration, a liquid droplet was put on a Langevin type vibrator, and ultrasonic vibration was applied to observe the change of the droplet shape. The droplets were deformed by the application of ultrasonic vibration, and the contact angle between solid and liquid was reduced, so that the wettability was improved. It was considered that the ultrasonic radiation pressure acting inside the droplet had an effect on the deformation of the droplet, and the value of the radiation pressure was estimated based on Laplace's equation. It was confirmed that when the viscosity of the liquid was high, the change in the shape of the droplet was prevented by an increase in the shear stress for deformation. Regarding the surface roughness, it was found that the pinning effect made it difficult to reduce the contact angle. When the ultrasonic vibration was stopped, the shape of the droplet recovered to some extent before the ultrasonic vibration, but did not completely return to the original shape.

Mass transfer is often the rate determining step for solid-liquid reaction, such as an electroplating process in automotive industry and a refining process in metallurgical industry. The decrease of concentration boundary layer thickness through the excitation of convection is adapted to enhance the solid-liquid chemical reaction rate. Therefore, traditional methods excite a macro-scale flow in the bulk liquid. Because the concentration boundary layer exists in the velocity boundary layer, the traditional methods have the limitation in enhancing mass transfer rate. Therefore, a new method was proposed, which imposes force directly near the solid-liquid interface. In the past research, force, with or without an oscillating component was imposed near the solid-liquid interface during the dissolution of a Cu anode into a Cu2+ aqueous solution. The increase of Cu2+ concentration under the force imposition with oscillating component was suppressed compared to that by imposing the force without oscillating component just above the center of the anode. This research evaluated the dissolved Cu2+ concentration distribution and the liquid flow pattern in the whole vicinity of the solid-liquid interface under the force imposition with or without oscillation component. The results indicated that by imposing the force with oscillating component, the increase of the Cu2+ concentration was suppressed in the whole vicinity of the solid-liquid interface, and the Cu2+ concentration distributed more uniformly near the solid-liquid interface. This might be because of the excitation of circulating micro-scale flows near the side parts of the anode surface.

In this paper, the radial electromagnetic force in the horizontal circular channel of an induction-heating tundish is derived. A dimensionless trajectory model of the inclusion is developed and numerically solved to acquire the trajectory of the moving inclusion. When the inclusion is in the lower half of the horizontal circular channel, the direction of the vertical component of the radial electromagnetic pinch force which acts on the inclusion is opposite to the buoyancy. Provided their magnitudes are the same, there is a balanced-position for the inclusions in a circular channel. Therefore, a dead-zone exists near the balanced-position, where the removal time of the inclusion with an AC magnetic-field is longer than without it. Then, the effect of the AC magnetic-field parameters on the range of the dead-zone is identified, which makes it possible to improve the removal efficiency of inclusions. The range of the dead-zone decreases with increasing magnetic-field intensity. When the dimensionless magnetic-field intensity is 56.3, the shielding parameter of 10-15.9 are optimal to decrease the range of the dead-zone.

We report on the influence of magnetic field strength on the alloy Tb0.27Dy0.73Fe1.95 during slow-cooling solidification. We examined the effect of magnetic field strength on microstructure, magnetization, and magnetostrictive properties of this giant magnetostrictive alloy. We found that after field-treated solidification, the microstructure of specimens had a distinct grain arrangement and displayed magnetic anisotropy. The crystal orientation changed from random in the field-free treatment to aligned along the 〈110〉 direction in flux densities of 1 and 2.2 T, and along the easy magnetization axis 〈111〉 at a flux density of 4.4 T. In consequence, the magnetostrictive coefficient of the samples under various stresses improved with increasing magnetic flux density. Both the d33 and k33 values and the energy transformation efficiency of the field-treated specimens showed strong enhancements.

An experimental investigation is carried out on the effects of a sudden contraction on the characteristics of an air-water two-phase flow in a millimeter-scale rectangular channel. The results reveal that the flow pattern transition types caused by sudden contraction can be basically classified into five. The scatter of the leading edge velocity of a bubble observed downstream of the sudden contraction increases as the channel height becomes smaller than a certain critical value. This phenomenon is not beneficial for practical usage of gas-liquid two-phase flows in micro channels.

International audience; Elicitation of crystallographic anisotropy is one of the promising methods for formation of functional materials because it enhances physical, chemical, mechanical and/or biological natures. Magnetic alignment is one of the powerful method of crystal alignment with magnetic susceptibility difference, in which operating parameters such as minimum intensity of the magnetic field and alignment time depend on the magnetic susceptibility difference. Thus, evaluation of the magnetic susceptibility difference of particles used as a raw material is essential for optimization of the crystal alignment process. However, it is different from that of a single crystal because particles used as a raw material is usually poly-crystals and/orcoagulated, and it might have distribution. In this paper, evaluation of distribution of the magnetic susceptibility difference of bismuth particles has been investigated.