<p>In this study, the efficiency of active flow-control devices was targeted by redesigning a vortex-based fluidic oscillator so that higher outlet jet-flow frequency could be obtained with lower internal pressure drop. In particular, these two are key metrics: higher oscillation frequencies enable more effective flow manipulation, while lower pressure losses reduce energy consumption. However, improvements in these performance metrics have traditionally been pursued through trial-and-error design iterations, which lack precision and require substantial computational effort. In this work, a gradient-based adjoint sensitivity analysis was employed as a design tool to systematically guide geometric modifications of the Coanda surface and feedback channel. The aim was to increase the jet oscillation frequency while reducing internal pressure losses. Two-dimensional unsteady Reynolds-averaged Navier–Stokes simulations using the Shear Stress Transport turbulence model were conducted to evaluate the proposed design modifications, and the computational results were validated against data from prior studies. The sensitivity-guided optimization indicated that subtle geometric changes can yield substantial benefits: for example, increasing the Coanda surface angle by 12° was found to raise the jet oscillation frequency by approximately 70% while lowering internal pressure losses by approximately 18% relative to the original design. It is demonstrated that these targeted, sensitivity-based modifications improve vortex dynamics within the oscillator and significantly enhance overall performance. Phase-portrait and spectral analyses were employed to confirm stable harmonic behavior and to reveal enhanced vortex coherence within the oscillator. Overall, this study deepens the understanding of fluidic oscillator behavior and provides practical guidelines for designing more efficient active flow control devices across a range of applications such as thermal-management applications.</p>