Numerical analysis and visualisation of energy flow by intensity vector method for a fluid-loaded structure

Abstract

The vibration energy flow in a fluid-loaded stiffened plate and the structural-acoustic coupling from the energy flow point of view are investigated using the intensity vector technique. The spatial distribution of the vibration and acoustic energy flow is visualised to show the position of energy source, the direction of flowing energy and the amount of radiation sound energy. The numerical results show that fluid loading changes the vibrational and sound energy flows. A spectrum plot shows that the structural-acoustic energy flow under air loading condition is generally at a smaller rate than that for the under water loading condition. From graphical plots, it is the sound energy flow, not the structural vibrational energy flow, that shows clearly the structural vibration mode shape. Furthermore, significant discrepancy is observed between the sound energy distribution near the surface of the plate and the vibration energy in the stiffened plate. An external damper significantly influences the vibrational and sound energy flows and the damping control strategies are investigated. Visualisations of the energy show that the damper should be placed close to the energy input source and more damping resulted in more energy dissipated.