Author(s)

B. Halvorsen & V. Mathiesen

Abstract

This paper presents an experimental and computational study of the bubble formation in a bubbling fluidised bed. The simulations are performed using a computational fluid dynamics (CFD) model named FLOTRACS-MP-3D proposed by Mathiesen et al. [l]. In order to reduce numerical diffusion and to study the effect of numerical schemes, the spatial first order upwind scheme is extended to second order in the momentum equations. Second order scheme may give unphysical and unbounded solutions. To avoid this, different flux limiters are tested. A two-dimensional lab-scale bubbling fluidised bed with a central jet is build. The bubble formation in the bed is visualised using a digital video camera. A comparison of simulation results with first and second order schemes shows that the numerical diffusion is reduced significantly, and that a more physically shaped bubble is formed with second order scheme.

Keywords