ABSTRACT
In this study, the transfer process of extremely light and small-sized particles along a defined direction without flipping them over on the transportation surface is evaluated by using a traveling wave. For this, the use of a liquid, as the contact layer injected onto the top surface of a piezoelectric traveling-wave device, is proposed to transmit the wave into the particles. As a preload is unlikely to be assigned here, the adhesion force between the lightweight particle and the liquid is expected to dominate the delivery effect. A short-beam linear motor is chosen as an example of a piezoelectric device that can generate a traveling wave in association with several selected liquids such as water, saline water, oil, and glycerol. The influence on the traveling-wave amplitude transmitted to liquids with different viscosities and heights is studied by an analytical approach and the finite-element simulation. The surface energy theory is used to determine the adhesion force between the liquid and the lightweight particle. An experiment is conducted to measure the speed of particles with variable sizes that are transported by the liquid wave. The analytical and experimental results are in good agreement, verifying the influence of the above concerned factors on the particle transfer speed.
Subject(s)
Computer SimulationABSTRACT
In magnetowetting, the material properties of liquid, surface morphology of solid, and applied external field are three major factors used to determine the wettability of a liquid droplet on a surface. For wetting measurements, an irregular or uneven surface could result in a significant experimental uncertainty. The periodic array with a hexagonal symmetry structure is an advantage of the anodic aluminum oxide (AAO) structure. This study presents the results of the wetting properties of magnetic nanofluid sessile droplets on surfaces of various AAO pore sizes under an applied external magnetic field. Stable, water-based magnetite nanofluids are prepared by combining the chemical co-precipitation with the sol-gel technique, and AAO surfaces are then generated by anodizing the aluminum sheet in the beginning. The influence of pore size and magnetic field gradient on the magnetowetting of magnetic nanofluids on AAO surfaces is then investigated by an optical test system. Experimental results show that increasing the processing voltage of AAO templates could result in enhanced non-wettability behavior; that is, the increase in AAO pore size could lead to the increase in contact angle. The contact angle could be reduced by the applied magnetic field gradient. In general, the magnetic field has a more significant effect at smaller AAO pore sizes.
