Inverse Energy Cascade Structure of Turbulence in a Bubbly Flow : (2nd Report, Numerical Analysis using Eulerian-Lagrangian Model Equations)

Abstract

The inverse energy cascade in bubbly flow is investigated by a numerical simulation using the Eulerian-Lagrangian model in which the governing equations are formulated with emphasis on the translational motion of bubbles in non-uniform flow. This paper is concerned with the validation of the numerical model and various parametric dependency on the inverse cascade. The calculated results reveal that, 1) continuous growth of the spatial fluctuation scale in a bubble-induced flow is well predicted by the present numerical model and the results have a good analogy with the experimental results which are introduced in our first report, 2) the strong relationship between energy-decaying process and bubble-bubble distance interval identified also by the present analysis, 3) the slope of energy-decaying at high wavenumber region depends on the kinetic viscosity of liquid, and that at low wave number region depends on inuniformity of buoyancy distribution which changes due to the bubble motion.