{'fraction_non_alphanumeric': 0.028766086298258896, 'fraction_numerical': 0.00984102952308857, 'mean_word_length': 4.508333333333334, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
On demand bubble generation in air: A mechanistic investigation

This study investigates single bubble formation from a nozzle connected to a T-junction supplied with polymer solution and air. The variables were the feed rates of the (two) polymer solutions and air, and the dimensions of the T-junction and nozzle. The T-junction arms were either both 1.1 or 2.2 mm, where the solution entered the junction horizontally and the air vertically from below. The upper arm of the junction was connected to a 3 mm tube on top of which was placed a nozzle with internal diameters of 1.6, 0.69 and 0.31 mm. Simultaneous feeding of solution and air to the junction, using metering syringes, resulted in successive slugs of liquid inter-spaced by air pockets. These ascended to the nozzle where bubbles formed. When the volumetric flow ratio of air:liquid is low, bubbles chain, i.e., the next slug arrives at the tip before the last bubble has burst. When the ratio is increased the bubbles burst before the next slug arrives. The transition between behaviours depends on the T-junction dimensions, ocurring at lower air:liquid ratios for the smaller T-junction. Narrower nozzles result in smaller maximum size bubbles, due to increased drainage of liquid down the outside of the nozzle before the air pockets can form a bubble.