“…to achieve a more intense (vigorous) spouting. Furthermore, the particle rotation is simultaneously increased to some extent, as found experimentally in [12] by means of magnet monitoring and by means of simulations with Discrete Particle Modelling (DPM) in [11,13]. However, regarding to the behaviour at increased gas velocities a negative property of this geometry was complained, namely a quickly growing flow instability, making the spouting stability highly dependent on the gas flow rate [10].…”