Quantifying Air Layer Dynamics During Water Entry Using Computational Fluid Dynamics

During water entry the impact forces associated with added mass can cause immense damage to the vehicle or body. It has been observed that certain impactor geometries can compress the air between themselves and the free surface right before impact. This air compression, referred to as the compressed air layer, acts as a spring and modifies the impact forces. This air layer adds an additional layer of complexity in the context of modeling the added mass forces during water entry. Furthermore, the peak impact force coefficient appears to vary non-linearly with the impact velocity indicating that the effect of the air layer is dependent on impactor geometry. We propose to utilize Computational Fluid Dynamics to analyze this problem by computing the impact forces for various impactor geometries and impact speeds. In the context of CFD, we explore the accessibility of data and emerging diagnostic methods, to better understand impact loads. Our aim is to utilize the numerical results to understand the physics of the air layer and to incorporate these physics into models for impact forces.