Fiber flocculation measurement in pipe flow by digital image analysis

The inherent tendency of fibers to crowd into mass concentrations or flocs gives rise to flow properties peculiar to fiber suspensions. The inhomogeneous spatial mass distribution depends on fiber properties, consistency and hydrodynamic quantities. The distribution of the structural scales of the inhomogeneous structure is indicative,e.g., of the flow state of the suspension. In several previous studies the flocculated state has been characterized using digital imaging and various image analysing methods. Our experimental setup consists of a flow loop with a transparent observation channel. The suspension is transilluminated and imaged with a fast-shutter CCD camera. The backgroung lighting is compensated using a large image statistics and taking into account the Lambert-Beer law. After image enhancement the statistical analysis is done.