Direct numerical simulations of stratified open channel flows

Nonlinear wave-wave interactions in stratified flows: Direct numerical simulations

To investigate the formation mechanism of energy spectra of internal waves in the oceans, direct numerical simulations are performed. The simulations are based on the reduced dynamical equations of rotating stratified turbulence. In the reduced dynamical equations only wave modes are retained, and vortices and horizontally uniform vertical shears are excluded. Despite the simplifications, our s...

Studies of Bubbly Channel Flows by Direct Numerical Simulations

Recent DNS studies of buoyant bubbly flows in vertical channels are discussed. Simulations of nearly spherical bubbly flows in vertical channels show that the bubbles move towards the wall for upflow and away from the wall for downflow in such a way that the core is in hydrostatic equilibrium. For downflow the wall layer is free of bubbles but for upflow there is an excess of bubbles in the wal...

Direct numerical simulations of two-layer viscosity-stratified flow

Two-dimensional simulations of flow instability at the interface of a two-layer, density-matched, viscosity-stratified Poiseuille flow are performed using a front-tracking/finite difference method. We present results for the small-amplitude (linear) growth rate of the instability at small to medium Reynolds number for varying thickness ratio n, viscosity ratio m, and wavenumber. We also present...

Direct Numerical Simulations of Three-Layer Viscosity-Stratified Flow

VOLUME 84, OCTOBER 2006 INTRODUCTION This work is motivated by a problem encountered in certain mixing processes that employ a centre line injector upstream of a static mixer. Static or motionless mixers have been adopted for a large number of blending and dispersion operations because they offer attractive features such as closed-loop operation, and no moving parts, in contrast to continuously...

Direct Numerical Simulations of Gas-Liquid Multiphase Flows