The method of lattice boltzmann equation(LBE) is a kinetic-based approach for fluid flow computations. In the last decade, minimal kinetic models, and primarily the LBE, have met with significant success in the simulation of complex hydrodynamic phenomena, ranging from slow flows in grossly irregular geometries to fully developed turbulence, to flow with dynamic phase transitions. In the presen...

The generalized Fick-Jacobs equation is widely used to study diffusion of Brownian particles in three-dimensional tubes and quasi-two-dimensional channels of varying constraint geometry. We show how this equation can be applied to study the slowdown of unconstrained diffusion in the presence of obstacles. Specifically, we study diffusion of a point Brownian particle in the presence of identical...

Aerodynamic forces acting on railway vehicles depend not only the shape of but also types infrastructure. In this study, leading car a train is simplified as finite-length square cylinder; and middle an infinite-length cylinder. We conducted large-eddy simulations (LES) flow around vehicle model flat ground, embankment viaducts. The LES results confirm that side force coefficients models change...

The physical characteristics of bifurcated states in systems with inherent symmetry are constrained in ways that those in systems with broken symmetry are not. Here we examine the issue of quasiperiodic versus subharmonic instability modes of time-periodic laminar wakes, and how the relationship between them is influenced by weak symmetry breaking. The examples used are the vortex street wake o...

Photonic band gaps in disordered two-dimensional photonic crystals are investigated for two typical types of randomness: cylinder site displacements ~site randomness! and cylinder radius variations ~size randomness!. The plane-wave expansion method with a supercell technique is applied to calculate the density-of-states ~DOS! for the disordered photonic crystals. In particular, numerical simula...