Fig. 3: Cooling mechanism regulated by acoustic frequency.

a Temperature decrease with acoustics ON at various acoustic frequencies (V = 0.1 m s⁻¹, q = 40 W cm⁻²). b Bubble size distribution with various acoustic frequencies (V = 0.1 m s⁻¹, q = 20 W cm⁻²), the horizontal axis represents the logarithmic scaling of bubble area pixel number distribution (lg). c Bubble numbers with various acoustic frequencies (V = 0.1 m s⁻¹, q = 20 W cm⁻²). d Simulation of the displacement of ALCHE with acoustics of 1.5 kHz. x and y represent the width and length direction of the microchannel. The blue circles in the figure represent the air bubbles. The black arrows represent the bubble migration direction. e Simulation of the displacement of ALCHE with acoustics of 7.5 kHz. The blue circles in the figure represent the air bubbles. The black arrows represent the bubble migration direction. f Visualization image of the bubble migration direction (V = 0.1 m s⁻¹, q = 20 W cm⁻²). The pink and blue arrows represent the bubble migration direction. g Schematic diagram of bubble tracking algorithm. t and t + Δt represent the image of a particular frame and the image of the next frame. The blue circles in the figure represent the air bubbles. Black arrows represent bubble migration distances (d). T_m (pink dashed line) represents the maximum displacement of the bubble, T_n (yellow dashed line) represents the neighborhood threshold of a given bubble, T_q (orange dashed line) represents the quasi-rigidity threshold. h Bubble trajectory length statistical results with acoustics off and on (V = 0.1 m s⁻¹, q = 20 W cm⁻²). The statistical distribution was obtained from Fig. 3i. i Bubble trajectories with acoustics off and on (V = 0.1 m s⁻¹, q = 20 W cm⁻²). Each image records four sets of bubble trajectories. The time interval for each trajectory is 11.25 ms. The black, pink and blue arrows represent the bubble migration direction.