Effect of fibres on hydrodynamic stability in a curved rotating channel

Authors: Kvick, M., Lundell, F., Prahl Wittberg, L., Söderberg, D.
Document Type: Conference
Pubstate: Published
Journal: 8th International Conference on Multiphase Flow (ICMF), Jeju, Korea (2013)
Year: 2013


Experiments and a linear stability analysis are performed for a range of flow velocities and rotation rates in a curved and rotating, high aspect ratio, rectangular, channel. The study is carried out in order to investigate the effect of Nano-Fibrillated Cellulose (NFC) on the hydrodynamic stability. In the experiments, the structures in the flow are visualised and images are acquired at a downstream position. In the linear stability analysis, the presence of fibres is modelled as an orientation dependent stress tensor, where the orientation is calculated based on Jeffery’s equations. A clear stabilisation is found when NFC is present, both in the experiments and in the theoretical work. However, this stabilisation is less than predicted by the effective viscosity. Moreover, the transient growth is found to a greater extent to be affected by the presence of fibres compared to the stabilisation, while the spanwise wavenumber is more or less unaffected.