Capillarity-induced resonance of oil blobs in capillary tubes and porous media

We investigate the excitation by sound waves of capillary trapped oil blobs The three-phase contact lines either remain pinned to the heterogeneities of the solid surface or slide if sound waves are applied. We derive approximate, analytical expressions for the resonance of oil blobs in capillary tubes for both types of contact line behavior. Based upon these simple model systems we conclude that resonance of oil blobs is significant for coarse-grained but not fine-grained media.