A concept to extract a feature of solid-air two-phase flow in a pipeline has been launched with a combination of a capacitance-computed tomography and wavelets transform. With this concept, particle distribution images obtained by CT are transformed with discrete wavelets multiresolution. As a result, in the case of low open area ratio of the pipe cross-section, high particle densities are shown in secondarily dominant levels as well as a substantial space level. The high value in the secondary level results from unhomogeneous density due to collision between particles and wall. In the experiment, the CT acquires the capacitances between 12 electrodes distributing around the outside of the pipeline. Clay is attached inside the pipeline in order to verify the open area ratio. The images are reconstructed from the capacitances with a linear back projection method.

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