Flute-like instruments with a stopped pipe were widely used in ancient cultures and continue to be used in many musical expressions throughout the globe. They offer great flexibility in the input control parameters, allowing for large excursions in the flux and in the geometrical configuration for the lips of the instrumentalist. For instance, the transverse offset of the jet axis relative to the labium can be shifted beyond the operational limits found in open-open pipes, and the total jet flux can be increased up to values that produce highly turbulent jets while remaining on the first oscillating regime. Some of the fundamental aspects of the acoustics and hydrodynamics of this kind of instrument are studied, like the instability of the jet wave and the static aerodynamic balance in the resonator. A replica of an Andean siku has been created to observe, through the Schlieren flow visualization, the behavior of both excitation and resonator of the instrument.