Solid obstacles can reduce hydrodynamic loading during water entry

The notion of sympathetic interactions between solids immersed in fluids is ubiquitous in applied physics, and the complexity of these interactions often results in unexpected outcomes. In this paper, we study the water entry of a rigid wedge in the presence of a neutrally buoyant solid cylinder below the water surface. We combine particle image velocimetry and direct measurements to elucidate the fluid-structure interaction. While the fluid confinement from the cylinder elicits a predictable increase in the pressure close to the keel, it is also responsible for a surprising reduction in the pressure toward the pileup. Through a detailed solution based on potential flow theory, we offer an explanation for this phenomenon. Our results may find application in the study of marine vessels that maneuver in occluded waters and seabirds that plunge and dive close to rocks or ice.