  This bachelor project presents a theoretical model describing the resonant
frequencies in rectangular and cylindrical tanks. It presents an experimental
validation in the rectangular case. The resonant frequencies are determined and
then used to construct a theoretical model for the free damping of viscous
fluids. The predictions of the model are qualitatively analysed. The higher the
resonant frequency, the higher the attenuation associated with that mode.
Adding a layer of a more viscous liquid, even a thin one, significantly
increases the attenuation. In addition, the addition of a layer of polystyrene
beads prevents excitation at low frequencies. However, experiments are still
needed to find out exactly what physical phenomena explain this. In addition.
Finally, an algorithm is designed and implemented in a Matlab code to determine
the behaviour of the liquid when subjected to a horizontal sinusoidal
excitation. The results of the algorithm are promising, but it still encounters
convergence problems for extreme cases. The algorithm can be used to make
theoretical predictions for rocket propellants. The application of this
research to the Bella Lui rocket of the EPFL rocket team is discussed.
