2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87798Here we show a complete band gap in acoustic propagation in water with regularly placed air-cylinders. Also for the first time, we report that in the gap, all cylinders oscillate in phase but exactly out of the phase of a wave source located inside the cylinder array.5 pages and 2 figuresFluid DynamicsGeneral Physicstext