Additional Evaluations of Gas Phase Effects on Slosh Dynamics with Commercial Codes

Liquid propellant slosh modelling classically relies on simplified analog models, typically derived from either potential flow solutions or constant-fill computational fluid dynamics (CFD) simulations, neglecting any impact of the gas phase. As the gas to liquid density ratio decreases, the importance of the gas phase inertia becomes significant, changing slosh dynamics. A recent work, “Gas Phase Effects on Slosh Dynamics” by Brodnick, Sansone, and Yang (2025), quantifies the impacts of the gas density ratio on slosh dynamics by using CFD simulations. The simulation cases of Brodnick et. al. are repeated and compared using alternative commercially available CFD codes to explore the generality and robustness of this method and other codes. Results from different codes compare well. This study expands on the previous work by also examining density ratios near unity, where buoyant forces nearly cancel forces due to acceleration, making the simulation analogous to low-gravity slosh situations. Results near density unity are compared to low-gravity slosh results to inform future evaluations of dynamic similitude using neutral buoyancy tests.