Reconstructed Holographic Image of Acoustic Cavitation Bubble Field

Holographic imaging

3D bubble field from acoustic cavitation in a cylinder. The bubbles have been recorded with high speed imaging of holograms. The image has been reconstructed and bubble sizes and positions are used to generated the above rendered image.

Cavitation Noise Spectra

Acoustic emission

Oscillating cavitation bubbles emit high intensity sound waves. Cavitation noise spectra as a function of the voltage of a driving piezoceramic cylinder are shown. The spectra are encoded in a grey scale. The frequency is scaled relative to the driving frequency of 71 kHz: Subharmonic frequencies and their harmonics appear while the driving amplitude is increased.

Listen to the cavitation noise, (wav-file, 131kB, pitch is transposed to an audible range) while the driving amplitude is increased. You'll hear period doubling (= frequency halfing) bifurcations into chaos.