Mixing time and kinetic energy measurements in a shaken cylindrical bioreactor

The mixing dynamics in a cylindrical shaken bioreactor are investigated by means of velocity and kinetic energy and mixing time measurements obtained with phase-resolved PIV and a dual pH indicator system, respectively. The objective of the work is to correlate the kinetic energy of the flow and the mixing number measured under different operating conditions. The results provide evidence that the onset of a laminar-turbulent flow transition occurs when the previously reported transition to out-of-phase flow takes place, and that the mixing number is highly dependent on the position of the feeding pipe. Insertion close to the vessel walls and thus outside the vortical structures present near the centre of the reactor can enhance mixing.