Figure 1.

Schematic of the experimental setups. (a–c) Three fluid mechanical systems exhibiting oscillatory instabilities, namely, a thermoacoustic, an aeroacoustic and an aeroelastic system respectively. In these fluid mechanical systems, the Reynolds number (Re) is the control parameter. (d) An optical system for random lasing, wherein we observe a transition towards narrow-band lasing like emission as we increase the excitation pulse energy (EPE) of the laser source. (e) Electronic circuit showing Chua’s circuit along with a zoomed detailed view of the Chua’s diode. The variable resistor (R) is varied to obtain the transition from a fixed point to limit cycle oscillations. In all these systems, we acquire data for different values of the respective control parameters. We measure the acoustic pressure fluctuations for thermoacoustic and aeroacoustic systems while the strain on the cantilever beam is acquired for the aeroelastic system. For the random laser, the output emission is collected using a fibre optic spectrometer and the voltage ($v_1$) is measured for the electronic circuit. The dimensions of different experimental setups are not to scale.