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Dynamics of bubble formation in highly viscous liquids
Ketan Pancholi1, Eleanor Stride, Mohan Edirisinghe
1Department of Mechanical Engineering, University College London, Torrington Place, London, United Kingdom.
Langmuir : the ACS Journal of Surfaces and Colloids
|March 12, 2008
Summary
Researchers studied microbubble formation in a T-junction device. Higher liquid flow rates and viscosities yielded smaller bubbles, crucial for ultrasound contrast agents and drug delivery.
Area of Science:
- Fluid dynamics
- Microfluidics
- Biomedical engineering
Background:
- Development of monodisperse microbubble suspensions is critical for ultrasound contrast agents and drug delivery.
- Applications demand high bubble uniformity and a maximum size of 8 µm.
- Understanding bubble formation in devices is key to achieving these requirements.
Purpose of the Study:
- To investigate bubble formation in a T-junction device.
- To determine the influence of processing parameters, particularly liquid viscosity, on bubble size.
- To correlate theoretical predictions with experimental observations.
Main Methods:
- Air bubble formation in a T-junction was visualized using high-speed cameras.
- Experiments were conducted with varying liquid to gas flow rate ratios (Ql/Qg) and liquid viscosities (µl).
- Theoretical predictions of flow profiles were based on axisymmetric Stokes flow analysis.
Main Results:
- Theoretical predictions of the flow profile were within 6% accuracy of experimental data.
- Both Ql/Qg and µl significantly influenced bubble formation and size.
- Increased flow rates and viscosities resulted in smaller bubbles, with diminishing returns beyond certain limits.
Conclusions:
- Axisymmetric Stokes flow analysis accurately describes bubble formation in T-junctions.
- Liquid viscosity and flow rate are critical parameters for controlling microbubble size.
- Optimal parameters can be identified to produce microbubbles suitable for medical applications.
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