The drag reduction technique involving air cavities under ship hulls is a promising energy-saving technology. Understanding the air cavity dynamics in unsteady conditions and developing methods for the air cavity system optimization are critically important for practical implementation of this technology. In this study, a potential-flow theory is applied for modeling the air cavities under solid walls in water flow with fluctuating pressure. The present modeling approach incorporates detachment of macroscopic air pockets from the cavity tail. For specific configurations considered in this article, it is found that a change of the rate of air supply into the cavity can partly mitigate degradation of the overall power savings by the air cavity system in unsteady conditions.
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