Plug flow of yoghurt in piping as determined by cross-correlated dual-plane electrical resistance tomography

Cross-correlation of electrical resistance tomography (ERT) was used to determine the velocity profile of yoghurt in a pipe of industrial dimensions. In viscometry, at shear rates higher than 10 s−1, the yoghurt followed the power law model with a K-value of 3.7 Pa sn and an n-value of 0.37. In pipe flow, however, within the tested mean velocity range of 0.05–0.25 m s−1, the yoghurt appeared to flow as a plug. The local velocity was constant from the centreline to within 3 mm of the tube wall, which corresponds to the resolution of the ERT method.