Improved three-dimensional color-gradient lattice Boltzmann model for immiscible multiphase flows

In this paper, an improved three-dimensional color-gradient lattice Boltzmann (LB) model is proposed for simulating immiscible multiphase flows. Compared with the previous three-dimensional color-gradient LB models, which suffer from the lack of Galilean invariance and considerable numerical errors in many cases owing to the error terms in the recovered macroscopic equations, the present model eliminates the error terms and therefore improves the numerical accuracy and enhances the Galilean invariance. To validate the proposed model, numerical simulation are performed. First, the test of a moving droplet in a uniform flow field is employed to verify the Galilean invariance of the improved model. Subsequently, numerical simulations are carried out for the layered two-phase flow and three-dimensional Rayleigh-Taylor instability. It is shown that, using the improved model, the numerical accuracy can be significantly improved in comparison with the color-gradient LB model without the improvements. Finally, the capability of the improved color-gradient LB model for simulating dynamic multiphase flows at a relatively large density ratio is demonstrated via the simulation of droplet impact on a solid surface.Comment: 9 Figure

Parametric cooling of a degenerate Fermi gas in an optical trap

We demonstrate a novel technique for cooling a degenerate Fermi gas in a crossed-beam optical dipole trap, where high-energy atoms can be selectively removed from the trap by modulating the stiffness of the trapping potential with anharmonic trapping frequencies. We measure the dependence of the cooling effect on the frequency and amplitude of the parametric modulations. It is found that the large anharmonicity along the axial trapping potential allows to generate a degenerate Fermi gas with anisotropic energy distribution, in which the cloud energy in the axial direction can be reduced to the ground state value

Alcohol Use, HIV Treatment Adherence, and Sexual Risk Among People with a History of Injecting Drug Use in Vietnam.

Alcohol use can limit the effectiveness of antiretroviral therapy (ART) for people living with HIV (PLH) who have a history of injecting drug use. This study described the patterns of alcohol use among PLH with a history of injecting drug use in Vietnam and examined the relationships between alcohol use, adherence to ART, and sexual risks. We utilized cross-sectional data of 109 PLH on ART collected from a randomized controlled intervention trial in Vietnam. Approximately 30 and 46% of the participants were frequent and occasional drinkers, respectively. Frequent drinkers reported the highest number of missed medication days. About 61% of frequent drinkers reported having sex after using alcohol. Additionally, 23, 34, and 24% of nondrinkers, occasional drinkers, and frequent drinkers, respectively, reported inconsistent condom use during sex. Future intervention programs should address the issues of alcohol use and sexual risks to maximize the effectiveness of HIV treatment programs in Vietnam