Fig. 5.

Emulsification modes in the WJR. The timestamp in milliseconds (ms) is indicated in the top left corner (a) Fine dispersion generation on the channel wall. The cavitation bubble on the channel wall oscillates and is encapsulated by an oil layer at 20 ms. The violent oscillation generates a fine dispersion. (b) A cavitation bubble situated in a pit (white dashed rectangle) ejects microbubbles which enter the oil slug (white dashed region on the oil slug). The microbubbles cluster (white dashed region at 10 ms) and oscillate violently to generate a fine dispersion (green dashed region at 50 ms). (c) An oil-encapsulated cavitation bubble (white dashed line at 0 ms) undergoes weak oscillation to generate large droplets (droplets inside green dashed line at 20 ms). (d) An oil-encapsulated cavitation bubble (white dashed line at 0 ms) ejects large oil droplets into the aqueous phase (droplets inside green dashed line at 1 ms).