Numerical investigation of the effect of aeration and hydroelasticity on impact loading and structural response for elastic plates during water entry

Abstract

This work presents a comprehensive numerical study of the impact of aeration and hydroelasticity on slamming loads and structural response of elastic plates during a water entry event. A numerical tool is developed with OpenFOAM and validated against experimental data from available benchmark tests. An extensive parameter investigation revealed that the structural flexibility of a plate exerts a noticeable effect on slamming loads for pure water entry cases, which almost completely disappears when the water is aerated. The effect of aeration on slamming loads is quite significant. With only 0.5 % air fraction, aeration can reduce substantially the peak slamming forces, but as the load duration increases at the same time the force impulse remains almost constant. The structural response, in terms of strain rates, reacts directly on the hydrodynamic loads for stiff plates, and exhibits resonating effects and less influence on aeration levels at higher flexibilities. This suggests that the structural performance in a slamming event must be carefully considered, and is only directly related to loads for very stiff structures. For this purpose, a new functional relation between peak impact forces/pressures and impact velocity in the presence of aeration is suggested within the present study.