Introduction <p>Effective control of sloshing in liquid storage tanks (LSTs) is essential for ensuring structural safety and reducing seismic-induced damage during earthquake events.</p> Purpose <p>This study evaluates the effectiveness of curved cylindrical dampers made of polyethylene (Pe), silicone (Si), and high-density polyethylene (Hdpe) at different liquid fill levels.</p> Methods <p>Numerical investigations were performed in ABAQUS employing the Arbitrary Lagrangian–Eulerian formulation. Seismic responses of liquid storage tanks with and without dampers were analyzed under Imperial Valley and Northridge earthquake ground motions.</p> Results <p>Hdpe dampers achieved a reduction of 43% in hydrodynamic pressures and 70.3% in sloshing amplitudes, showing better performance than Pe and Si dampers. Although all dampers contributed to seismic response mitigation, Hdpe provided more consistent control of impulsive pressures and sloshing motions across all liquid levels.</p> Conclusions <p>The results highlight the significance of damper material selection in sloshing mitigation. Curved cylindrical dampers made of Hdpe offer a more reliable solution for improving the seismic performance of liquid storage tanks.</p>