eDespite its,wide applications, fluidization is not understood enough to satisfy our technical or academic interests. Cascading simulation approaches on different scales, with small-scale approaches provide constitutional correlations to larger scale approaches, is considered a practical way toward this direction. However, by physically reproducing many macro-scale phenomena in fluid flow and fluidization on micro-scales even below the traditional continuum limit, pseudo-particle modeling (PPM,. Ge and Li (Proceedings of the Fifth International Conference on Circulating Fluidized Bed, Beijing, China, Science Press, Beijing, 1996) has suggested the possibility of a more straightforward and penetrating way. In this paper, traditional approaches are reviewed first and then PPM is discussed in full length and validated further. We demonstrate that it has maintained all necessities on the molecular level for comprehensive flow description, and the reproduced phenomena, such as bubbling, clustering and radial heterogeneity, have reflected the fundamental mechanism of their macro-scale counterparts despite the vast scale difference. With this digital miniature, every detail of the flow can be traced non-intrusively until the lowest level in classic physics and experiment with flexible parameters, which provides a unique tool for, theoretical study and engineering predictions. Therefore, PPM is at least a useful complement, if not substitute, to traditional approaches. (C) 2003 Elsevier Science Ltd. All rights reserved.