Direct numerical simulation of multiphase flows

Recent development for the direct numerical simulation of dispersed multiphase flows is reviewed. A current trend is to use the fixed Cartesian mesh, because it is suited to deal with multiple solids, bubbles and/or droplets. Features of typical methods for gas-liquid interfaces and solid-fluid boundaries are discussed. For gas-liquid interfaces, existing methods are categorized into fitting, tracking, capturing and transportation methods in order to clarify their characteristics. For deformable solid objects moving in a fluid, on the other hand, schemes based on the immersed-boundary method are highlighted. Our prime interest is in the conservation properties of the algorithms. From such a viewpoint, we propose the combination of volume-of-fluid (VOF) method and the velocityfield overridden by immersed solid (VOIS) method for flows laden by multiple bubbles and particles.