Study of the fluid effects on a submerged circular plate
Tutor / director / evaluatorEscaler Puigoriol, Francesc Xavier
Document typeBachelor thesis
Rights accessOpen Access
In this study, numerical analyses were performed to determine the effects of water loading and fluid-structure interactions on the axisymmetric modes of vibration of a free circular Chladni plate. A coupled structural-acoustic finite element model was built to study the modal properties of the circular plate. With structural modal and modal acoustic analyses, the axisymmetric natural frequencies and the mode shapes were determined for the plate in vacuum, in air and fully submerged in water. Numerical results were validated with theoretical results computed for the model plate. A better agreement was obtained in the vacuum and air cases, compared to the water results. The natural frequencies were seen to reduce due to the added mass effects of water, with an average frequency reduction ratio of 66,7%. On another hand, the mode shapes in water were also observed to change and differences between dry and wet modes were measured with the radii calculation of the nodal circles. Then, the effect of a solid boundary proximity on the axisymmetric modes was studied for the plate submerged in water. At different distances between the plate and the bottom wall, the natural frequencies were determined for the first 4 axisymmetric modes. A clear frequency reduction was observed as the wall got near to the plate. Variations within the different axisymmetric modes were quantified computing the frequency ratios for every relative wall distance. Finally, two-way coupled Fluid-Structure Interaction (FSI) transient simulations were performed for the Chladni circular plate in water. The interactions between the fluid and the plate were studied when the plate is fixed at its centre.