Simulating shock interaction with a cavity-embedded cylinder/droplet using a real-fluid hybrid scheme at near-critical conditions

Examining the influence of shock waves on cylinders and droplets at near-critical conditions, especially when accounting for real fluid effects, represents a relatively unexplored frontier. This research gap becomes even more relevant when extending the investigation to three-dimensional scenarios. The underlying evolution mechanisms at these conditions remain elusive, with limited existing literature. In this study, we present a thorough exploration employing two-dimensional and three-dimensional numerical simulations of a droplet with an embedded gas cavity subjected to a normal shock wave at near-critical conditions. Our approach involves modeling the cylinder/droplet and the surrounding gas flow using the compressible multicomponent equations, incorporating real fluid thermodynamic relationships, and implementing a finite-volume-based hybrid numerical framework capable of capturing shocks and interfaces. To establish the reliability of our approach, we validate it against reference data, demonstrating excellent agreement. We also conduct mesh independence studies, both qualitatively and quantitatively. Our analysis is comprehensive, considering the intricacies of shock impingement, the morphological deformation of the cylinder/droplet and cavity, and the development of vortices. We discuss and analyze various phenomena, including the evolution of wave patterns, jet formation, sheet formation, hole appearance, the emergence of petal-shaped structures or lobes, ligament formation, shear-induced entrainment, and internal cavity (bubble) breakup. We compare the results obtained from the cylinder/droplet with a cavity to those from a planar shock wave impacting a pure cylinder/droplet. We provide a holistic view of the two-dimensional cylinder and three-dimensional droplet's evolution before and after the impact of a shock wave, accompanied by quantitative data regarding the positions of characteristic points along the column over time. Our analysis further scrutinizes the geometrical characteristics of the cylinder and the trends in the distribution of baroclinic vorticity at various stages. Our findings reveal that the presence of a gas cavity plays a pivotal role in shaping the shock wave, which, in turn, influences the generation and distribution of baroclinic vorticity. This leads to a transformation in the unstable evolution process of both the cylinder and the droplet. Importantly, shock waves impacting the evolving interfaces of the cylinder/droplet and the internal gas cavity generate baroclinic vorticity, which subsequently affects the transport and distribution of vorticity, thereby influencing the evolution of the cylinder/droplet interface. In the case of three-dimensional droplets, baroclinic vorticity induces complex, intricate three-dimensional structure transformations.     «

Examining the influence of shock waves on cylinders and droplets at near-critical conditions, especially when accounting for real fluid effects, represents a relatively unexplored frontier. This research gap becomes even more relevant when extending the investigation to three-dimensional scenarios. The underlying evolution mechanisms at these conditions remain elusive, with limited existing literature. In this study, we present a thorough exploration employing two-dimensional and three-dimension...     »