A Numerical Model of the Flow Past a Spherical-Cap Bubble Rising in a Fluidized Bed

Abstract

The shape and motion of gas bubbles in a fluidized bed are investigated by considering a single spherical-cap bubble rising vertically with free slip at its surface in an incompressible Newtonian fluid. The bubble shape, its terminal rise velocity, and the flow pattern around the bubble have been computed numerically by use of a finite element package solving the Navier-Stokes flow equations. Comparison with experimental findings shows that the bubble shape and the wake fraction can be predicted satisfactorily for a range of bubble sizes by assuming that the fluidized bed behaves as a Newtonian fluid. However, a clear-cut discrepancy was found in the terminal rise velocity. The results indicate that this discrepancy cannot be fully explained from the a priori assumption of the spherical-cap bubble shape, but that, most probably, some nonNewtonian fluid behavior must be invoked.

How to estimate added mass of a spherical cap body: Two approaches

“…Jackson, 2000 and other earlier standard texts on fluidized bed), and still is a vital part of current modelling efforts (e.g. Hoogstraten et al, 1998;Villa Briongos et al, 2011). On the more theoretical, fluid mechanical side, analytical studies were performed when possible, typically in the laminar case (e.g.…”

Recirculation within a fluid sphere at moderate Reynolds numbers

“…Based on those crucial experiments, the theory of Harper & Moore (1968) is currently preferred to that of Parlange (1970) (e.g. Dandy & Leal 1989;Fan & Tsuchiya 1990;Hoffmann & van den Bogaard 1995;Hoogstraten et al 1998).…”