A numerical algorithm for the analysis of the bubble dynamics in two-dimensional fluidized beds simulated by means of CFD multiphase-flow codes

The present article describes an algorithm developed for computing the position and the equivalent diameter of bubbles featuring in two-dimensional fluidized beds simulated by means of Computational Fluid Dynamics (CFD) multiphase-flow codes. The program is presented for two-dimensional systems; nevertheless, following the same logic herein outlined, it can be easily extended to the more general case of three-dimensional beds. In this work, by "equivalent diameter" it is meant the diameter of the circle having the same area as the bubble. The procedure is intended as a useful tool in the validation of the results of numerical simulations aimed at investigating the fluid-dynamic behavior of fluidized beds operating in the bubbling regime. The algorithm, presented here without making reference to any specific programming language, can be run in any CFD commercial code, provided that the language and the syntax used are consistent with those required by the particular code adopted. The logic of the program is first illustrated in general terms, and afterwards by making reference to an illustrative example regarding a Geldart Group B powder fluidized by means of air. In this specific case, the equations of motion used to describe the dynamics of the system have been based on the work by Mazzei et al. (2006), the commercial CFD code used has been CFX 4.4 and the programming language applied to implement the algorithm has been Visual Fortran 6.6.