Capillary filling for multicomponent fluid using the pseudo-potential Lattice Boltzmann method

We present a systematic study of capillary filling for a binary fluid by using mesoscopic a lattice Boltzmann model describing a diffusive interface moving at a given contact angle with respect to the walls. We compare the numerical results at changing the ratio the typical size of the capillary, H, and the wettability of walls. Numerical results yield quantitative agreement with the theoretical Washburn law, provided that the channel height is sufficiently larger than the interface width and variations of the dynamic contact angle with the capillary number are taken into account.     

Lattice mesoscopic model of dynamically heterogeneous fluids

We introduce a mesoscopic three-dimensional lattice Boltzmann model which attempts to mimic the physical features associated with cage effects in dynamically heterogeneous fluids. To this purpose, we extend the standard lattice Boltzmann dynamics with self-consistent constraints based on the nonlocal density of the surrounding fluid. The resulting dynamics exhibits typical features of dynamic heterogeneous fluids, such as non-Gaussian density distributions and long-time relaxation. Because of its intrinsically parallel dynamics, and absence of statistical noise, the method is expected to compute significantly faster than molecular dynamics, Monte Carlo, and lattice glass models.     

Lattice Boltzmann across scales: from turbulence to DNA translocation

The capability of the lattice Boltzmann (LB) method to describe complex flow behaviour across a wide range of scales of motion is discussed. This capability is illustrated by means of three examples, straddling across over ten decades of fluid motion, from macroscopic turbulence, to microfluidics, all the way down to nanoscopic flows of biological interest. It is pointed out that each of these applications requires extensions of the original LB scheme, beyond the realm of Navier-Stokes hydrodynamics for which the method was originally designed. The main qualitative ideas behind such extensions are discussed and commented on, with special emphasis on their direct ties with modern non-equilibrium statistical mechanics.     

Relativistic lattice kinetic theory: Recent developments and future prospects

In this paper, we review recent progress in relativistic lattice kinetic theory and its applications to relativistic hydrodynamics. Two methods for constructing the discretised distribution function, moment matching and projection onto orthogonal polynomials, are described. Extensions to ultra-high velocities as well as improved dissipation models are discussed. We show that the existing models can successfully cover a wide range of velocities (from weak-relativistic to ultra-relativistic) and viscous regimes. Various applications, from quark-gluon plasma and relativistic Richtmyer-Meshkov instability to flows in curved manifolds are also explored. Finally, potential developments for general relativity are outlined along with future prospects for solving the full set of Einstein equations of general relativity.     

A fluctuating lattice Boltzmann scheme for the one-dimensional KPZ equation

Based on the well-known mapping between the Burgers equation with noise and the Kardar–Parisi–Zhang (KPZ) equation for fluctuating interfaces, we develop a fluctuating lattice Boltzmann (LB) scheme for growth phenomena, as described by the KPZ formalism. A very simple LB-KPZ scheme is demonstrated in 1+1 spacetime dimensions, and is shown to reproduce the scaling exponents characterizing the growth of one-dimensional fluctuating interfaces.     

Multiscale Lattice Boltzmann Schemes with Turbulence Modeling

The viability of multiscale lattice Boltzmann schemes for the numerical simulation of turbulent flows is discussed and numerically demonstrated for turboaxial machine applications. The extension of boundary-fitting formulas based on wall functions is proposed, which enables the efficient computation of turbulent flows in complex curvilinear geometry using a simple Cartesian grid. Examples of two-dimensional turbulent flows in an axial compressor cascade are presented.     

Lattice Boltzmann model for anisotropic liquid-solid phase transition

We develop a simple reaction model for the liquid-solid phase transition in the context of the lattice Boltzmann method with enhanced collisions. Calculations for a two-dimensional test problem of Ga melting and for a two-dimensional anisotropic growth of dendrites are presented and commented on.     

Lattice Boltzmann Simulation of Reactive Microflows over Catalytic Surfaces

We investigate the effects of geometrical micro-irregularities on the conversion efficiency of reactive flows in narrow channels of millimetric size with heterogeneous catalysis. Three-dimensional simulations, based upon a Lattice-Boltzmann-Lax–Wendroff code, indicate that micro-corrugations may have an appreciable effect on the effective reaction efficiency of the device. Once extrapolated to macroscopic scales, these effects can result in a sizeable increase of the overall reaction efficiency.     

Propeller tone bursts

Intense high frequency (25–38 kHz) tone bursts have been observed in acoustic tests of a scale model of a general aviation propeller. The amplitude of the tone burst is approximately equal to the amplitude of the propeller noise signature. The conditions necessary for the production of these tone bursts are described. The experiments indicate that the origin of these bursts is a periodic flow oscillation on the suction surface of the propeller blade tips which may be due to the interaction between an oscillating shock wave and a laminar boundary layer.