Application of X-ray microtomography to numerical simulations of agglomerate breakage by distinct element method

Computer-aided tomography has been used for many years to provide significant information about the internal properties of an object, particularly in the medical fraternity. By reconstructing one-dimensional (ID) X-ray images, 2D cross-sections and 3D renders can provide a wealth of information about an object's internal structure. An extension of the methodology is reported here to enable the characterization of a model agglomerate structure. It is demonstrated that methods based on X-ray microtomography offer considerable potential in the validation and utilization of distinct element method simulations also examined.

X-ray microtomography of 410 million-year-old optic capsules from placoderm fishes

The structure of two small ossified optic capsules from mid-Palaeozoic placoderm fishes has been revealed in fine detail, by the use of Xray microtomography analysis and 3D visualisation software. These two specimens are 410 million-year-old; they were collected from an Early Devonian (Lochkovian) limestone in central New South Wales, and are the oldest known optic capsules from jawed fishes. The capsules show attachment areas for seven extrinsic eye muscles, rather than the six until recently deemed universal for gnathostomes. The analysis also revealed structures within the ossified cartilage which covered the medial surface of the eyeball, including nerve tracts, vascular canals, and possibly a choroid rete mirabile. (c) 2005 Elsevier Ltd. All rights reserved.

Local liquid holdups and hysteresis in a 2-D packed bed using X-ray radiography

An X-ray visualization technique has been used for the quantitative determination of local liquid holdups distribution and liquid holdup hysteresis in a nonwetting two-dimensional (2-D) packed bed. A medical diagnostic X-ray unit has been used to image the local holdups in a 2-D cold model having a random packing of expanded polystyrene beads. An aqueous barium chloride solution was used as a fluid to achieve good contrast on X-ray images. To quantify the local liquid holdup, a simple calibration technique has been developed that can be used for most of the radiological methods such as gamma ray and neutron radiography. The global value of total liquid holdup, obtained by X-ray method, has been compared with two conventional methods: drainage and tracer response. The X-ray technique, after validation, has been used to visualize and quantify, the liquid hysteresis phenomena in a packed bed. The liquid flows in preferred paths or channels that carry droplets/rivulets of increasing size and number as the liquid flow rate is increased. When the flow is reduced, these paths are retained and the higher liquid holdup that persists in these regions leads to the holdup hysteresis effect. Holdup in some regions of the packed bed may be an order of magnitude higher than average at a particular flow rate. (c) 2005 American Institute of Chemical Engineers