Considering the velocity ratio, for the use of coarse magnesium turnings the optimum (Bo ≈ 80) lies within a range of Ψ=3-8, depending on the amplitude (figure ). For the finer magnesium turnings, the highest Bo can be obtained by using a stroke volume of 10 µl and by using this value elevated Bo due to oscillatory flow are possible up to Ψ=8 (figure ). Therefore, independent of the used size of magnesium turnings, the optimum in terms of Bo and a minimum in axial dispersion can be realized by paying attention to a velocity rate below 8. For smaller particles, the optimum velocity ratio is lower as for larger particles. The optimal range of velocity ratio values found for the reactor investigated in this work are comparable to results by P. compaction in between measurement runs, but not during actual residence time measurements. Using coarse magnesium turnings and low oscillatory Reynolds numbers, a Bodenstein number of 47 is achieved, while a maximum of 80 is possible at higher Reynolds numbers. This range of Bo correlates to the Bodenstein numbers at 2 mL/min found for non-oscillating flow conditions (figure ) and indicates a similar influence of the vibrations introduced by the jogging motor and the oscillatory flow on the actual flow behaviour within a bed of coarse magnesium turnings. When using fine turnings, the vibrations generated by the jogging motor during measurements were not sufficient to reduce the axial dispersion, but a superimposed oscillatory flow does. The Bodenstein numbers could be increased up to 230. For coarse as well as fine magnesium turnings the optimum oscillatory Reynolds number achieving the highest Bodenstein numbers lies in a range of 0 to 1.5. Fine tuning of operational conditions is easier manageable by using oscillatory flow instead of a jogging motor, but since oscillatory flow will not lead to compaction of the magnesium bed, the use of the jogging motor and its influence is not negligible.