Ultrasonic levitation of some small living animals such as ant, ladybug, and young fish has been achieved with a single-axis acoustic levitator. The vitality of ant and ladybug is not evidently influenced during the acoustic levitation, whereas that of the young fish is reduced because of the inadequacy of water supply. Numerical analysis shows that the sound pressures on the ladybug’s surface almost reach the incident pressure amplitude p0 due to sound scattering. It is estimated that 99.98% of the acoustic energy is reflected away from the ladybug. The acoustic radiation pressure pa on the ladybug’s surface is only 1%–3% of p0, which plays a compression role on the central region and a suction role on the peripheral region.

We have studied the coalescence of bubbles in electrolyte solutions by measuring the fraction of contacting bubble pairs that coalesce as a function of electrolyte concentration. At low concentrations, we have reproduced earlier results in the literature, but by extending our measurements to higher electrolyte concentrations, we have found that some electrolytes previously thought not to inhibit bubble coalescence do show a transition to coalescence inhibition at higher (>1 M) concentrations. These results suggest that coalescence inhibition should be studied over wider concentration ranges if full insight into the factors governing coalescence inhibition is to be obtained.

Single-axis acoustic levitation of the heaviest solid (iridium, rho=22.6 g cm(-3)) and liquid (mercury, rho=13.6 g cm(-3) on the Earth is achieved by greatly enhancing both the levitation force and stability through optimizing the geometric parameters of the levitator. The acoustically levitated Pb-Sn eutectic alloy melt (rho=8.5 g cm(-3)) is highly undercooled by up to 38 K, which results in a microstructural transition of "lamellae-broken lamellae-dendrites." The drastic enhancement of levitation capability indicates a broader application range of single-axis acoustic levitation.

The supercooling and nucleation of acoustically levitated water drops were investigated at two different sound pressure levels (SPL). These water drops were supercooled by 13to16K at the low SPL of 160.6dB, whereas their supercoolings varied from 5to11K at the high SPL of 164.4dB. The maximum supercooling obtained in the experiments is 32K. Statistical analyses based on the classical nucleation theory reveal that the occurrence of ice nucleation in water drops is mainly confined to the surface region under acoustic levitation conditions and the enlargement of drop surface area caused by the acoustic radiation pressure reduces water supercoolability remarkably. A comparison of the nucleation rates at the two SPLs indicates that the sound pressure can strengthen the surface-dominated nucleation of water drops. The acoustic stream around levitated water drops and the cavitation effect associated with ultrasonic field are the main factors that induce surface-dominated nucleation.

Many functional materials have been used in oil and gas industries. Special materials were needed for to withstand the high temperature and pressure harsh environment of oil and gas reservoir. Nanotechnologies have the potential to introduce revolutionary changes of materials used in the areas of the oil and gas industries. This paper gives an overview of the nanotechnology application for enhanced oil recovery, fracturing fluids, flow assurance, drilling, completion and specialty composite in the oil and gas industry in the last few years. Applications of nano-materials, in the form of solid composites and functional nanoparticle-fluid in these areas are reviewed. The future challenges of nanotech-based solutions for the petroleum industry are also discussed.