The effect of numerical diffusion on simulation of isolated bubbles in a gas-solid fluidized bed

A two-fluid hydrodynamic model of a two-dimensional gas-solids fluidized be d is used to calculate the shape of an isolated bubble. The calculations ar e done by applying four different discretization schemes to the convection term. The bubble shape calculated by using the first-order upwind (FOW) sch eme is unphysical and pointed, where as the bubble shape calculated by the second-order schemes SMART, Superbee, and MINMOD is physically realistic an d rounded. Grid independence of the solutions is established. Superbee and SMART are found to give the most accurate results for a given grid resoluti on. Higher order discretization schemes are implemented with a downwind fac tor (DWF) method and with a deferred correction (DC) method. The DC method is significantly faster than the DWF method. (C) 2001 Elsevier Science B.V. All rights reserved.