The water entry of a simple harmonic oscillator

Understanding the slamming forces that occur when a blunt object impacts the air-water interface is critical to the design of engineered systems. Here, we evaluate how the structural rigidity and conical opening angle of an axisymmetric impactor simultaneously influence the resultant slamming force. Our previous work with sprung hemispherical noses demonstrated that the impact force relative to that of a fully rigid counterpart is defined by a non-dimensional hydroelastic factor, representing a ratio of hydrodynamic to elastic timescales. By exploring the effect of nose geometry in this problem, we extend our prior experimental results and provide a unified collapse of our data across nose geometries, stiffnesses, and impact speeds, directly informed by analysis of our companion reduced-order model. Our experimental data is further compared directly to the model predictions, offering fundamental insights into impact force mitigation via impactor elasticity.