Mode transition of a flue organ pipe

A flue organ pipe can be excited in various acoustic modes by changing the air pressure supplied to it. This research aims to reconstruct this behavior from the result of numerical flow simulation of a jet deflected by sound and from physical modeling simulation of the total sound production system. In the numerical flow simulation, motion of the jet in the pipe mouth was replicated: The jet emerges from a flue and travels in a space where the air oscillates laterally to the jet direction. As a result, the jet oscillates with the same frequency as the oscillation of the air i.e., sound. From the flow simulation, a model of the jet deflection was developed. This model was then used as a model of the sound source in the physical modeling simulation where not only the sound source but the resonance of the pipe is also modeled in a set of differential equations with delayed feedback. The mode transition observed in the physical modeling simulation was discussed by comparing with that experimentally observed.