A circulation-controlled wing has the potential to significantly increase lift, however, at the cost of in creased noise. In this study, we use Overset-LES to explore the noise reduction capabilities of applying porous materials to such a circulation-controlled wing. The presence of a porous medium in the flap allows airflow to pass through, in contrast to a non-porous flap configuration. Consequently, the boundary layer on the flap’s suction side thickens considerably. This study provides insights into the role of flow-through behavior in porous materials and its effect on boundary layer thickening, highlighting the need to moderate this phenomenon to achieve effective noise reduction. Additionally, the findings underscore the significance of curvature noise, which should be the primary focus to reduce noise of circulation-controlled wings.