Validation and application of the lattice Boltzmann algorithm for a turbulent immiscible Rayleigh–Taylor system

We develop a multicomponent lattice Boltzmann (LB) model for the two-dimensional Rayleigh–Taylor turbulence with a Shan–Chen pseudopotential implemented on GPUs. In the immiscible case, this method is able to accurately overcome the inherent numerical complexity caused by the complicated structure of the interface that appears in the fully developed turbulent regime. The accuracy of the LB model is tested both for early and late stages of instability. For the developed turbulent motion, we analyse the balance between different terms describing variations of the kinetic and potential energies. Then we analyse the role of the interface in the energy balance and also the effects of the vorticity induced by the interface in the energy dissipation. Statistical properties are compared for miscible and immiscible flows. Our results can also be considered as a first validation step to extend the application of LB model to three-dimensional immiscible Rayleigh-Taylor turbulence. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

On a new method for regularizing equations two-phase incompressible fluid

This paper presents a new method for the numerical simulation of two-phase incompressible immiscible flows. The methodology is based on the hydrodynamic equations regularization method using the quasi-hydrodynamic approach. Two systems of regularized equations are developed, which differ in terms of velocity regularization. The comparison of the described equations systems and the approbation of the numerical model on two numerical tests are given: dam break problem with the bottom step, for which the experimental data are described (Koshizuka’s experiment), and the cubic drop evolution problem. The latter problem is a model one with artificially specified parameters that demonstrates the effects of surface tension. A numerical model of two-phase flows is implemented in the open-source platform OpenFOAM using the finite volume method.

Optofluidic restricted imaging, spectroscopy and counting of nanoparticles by evanescent wave using immiscible liquids

An integrated optofluidic chip for restricted imaging, spectroscopy and counting of nanoparticles using the evanescent wave of total internal reflection at the interface of immiscible flows.