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Updated: Jul 4, 2025

Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions
Published on: February 17, 2019
New insights into antibubble formation by single drop impact on a same-liquid pool
1Department of Food Science, College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al Ain 15551, United Arab Emirates.
Secondary drops (SDs) from falling drops can create antibubbles. This study reveals new formation mechanisms and predicts antibubble size and probability using parameters like falling-drop height and surfactant concentration.
Area of Science:
- Fluid dynamics
- Surface science
- Colloid and interface science
Background:
- Secondary drops (SDs) are formed when falling drops impact a liquid bath.
- These SDs can potentially generate antibubbles, which are bubbles within a bubble.
- Understanding antibubble formation is crucial for various applications.
Purpose of the Study:
- To identify mechanisms of antibubble formation from secondary drops.
- To predict the size and formation probability (PAb) of antibubbles.
- To explore the influence of parameters like falling-drop height and surfactant concentration.
Main Methods:
- Generating secondary drops using a stable pulseless microfluidic pump.
- Recording drop impacts with a high-speed camera.
- Analyzing SD and antibubble formation, size, and probability based on falling-drop height (HFD) and dimensionless parameters (e.g., Weber number).
Main Results:
- New antibubble formation mechanisms from SDs were identified.
- Increased falling-drop height, impact velocity (U), and Weber number (We) led to larger SDs and antibubbles but fewer SDs.
- Antibubble formation probability showed distinct peaks related to HFD, U, and We, influenced by surfactant concentration.
Conclusions:
- Surfactant concentration plays a critical role in antibubble formation, with an optimal range for enhanced probability.
- Artificial neural modeling successfully predicted antibubble formation.
- Findings offer insights for controlled antibubble generation.
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