Development and evaluation of a model for soil-air fluidized bed rheological behavior

The ground vehicle mine blast mitigation problem represents a research topic that has recently been generating a very high level of interest and activity. Many aspects of the physics of the problem have been extensively researched. One area that has been neglected, however, is that aspect of the blast threat that relates to the rheology and flow, subsequent to ignition of the explosive, of the relatively energetic mixture of air and soil, sometimes referred to as ejecta. Methods developed for the study of fluidized beds that are used in, e.g. the chemical and power generation process industries, were adapted in order to more clearly define the rheology of air-glass bead mixtures and also of air-soil mixtures that comprise the ejecta. Continuity and momentum balance equations developed for fluidized beds were adapted, using physical properties of glass beads and soils, into a form relates to the properties of mine blast ejecta. These equations were then discretized and solved, for a relatively simple geometry, in order to validate the model and gain a general sense of the flow behavior of particle-air blends. Parametric studies were performed to estimate the variation of the rheology of the air-particle mixtures as a function of the particle diameter and the sphericity of the particles. Finally, the flow properties of a couple of real soils were investigated via application of the two-phase flow model.