Lattice Boltzmann Methods for Multiphase Flow Simulations across Scales - Volume 9 Issue 2 - Giacomo Falcucci, Stefano Ubertini, Chiara Biscarini, Silvia Di Francesco, Daniele Chiappini, Silvia Palpacelli, Alessandro De Maio, Sauro Succi

In this work, a hybrid lattice Boltzmann method (HLBM) is proposed, where the standard lattice Boltzmann implementation based on the Bhatnagar-Gross-Krook (LBGK) approximation is combined together with an unstructured finite-volume lattice Boltzmann model. The method is constructed on an overlapping grid system, which allows the coexistence of a uniform lattice nodes spacing and a coordinate-free lattice structure. The natural adaptivity of the hybrid grid system makes the method particularly suitable to handle problems involving complex geometries. Moreover, the provided scheme ensures a high-accuracy solution near walls, given the capability of the unstructured submodel of achieving the desired level of refinement in a very flexible way. For these reasons, the HLBM represents a prospective tool for solving multiscale problems. The proposed method is here applied to the benchmark problem of a two-dimensional flow past a circular cylinder for a wide range of Reynolds numbers and its numerical performances are measured and compared with the standard LBGK ones.

During the last decade, the lattice Boltzmann (LB) method has captured an increasing attention as an efficient tool for the numerical simulation of complex fluids, particularly multiphase and multicomponent flows. In this paper, we revisit the basic features of two modern variants of LB models for non-ideal fluids, which offer promising perspectives for the numerical simulation of complex microflows.