For the measuring system only the eigenfrequencies and eigenmodes with fluid-solid interaction are of interest. The modes with fluid motion alone are not relevant and, consequently, not included in the presented results. As calculated in the separate CFD simulations, the particles in this case stay at the bottom part of the bottle in a range between 0 up to 15 mm from below. A further result of all modal analysis calculations lies in the importance of the frequency range from f = 250Hz up to some kHz with respect to a suitable tolerance. Because of the big motion at maxima and minima of eigenmodes of lower order in the zone of detection, as shown in the Figs. 7, 10, 11, 13, 16 and 17, a great influence of the bottle onto the measuring sensor can be detected. In addition it is necessary to compare the calculations of the modal analysis with measurements. The whole filling machine has to be taken into account to improve the knowledge of the relevant influences. Experimental detection is possible by the presentation of system response against modal values and excitation frequency [2].
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