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Limiting conditions for applying the spherical section assumption in contact angle estimation.
1Unilever Research India, C/O Hindustan Lever Research Centre, BD Sawant Marg, Andheri (E), Mumbai 400099, India. jaideep.chaterjee@unilever.com
Journal of Colloid and Interface Science
|March 26, 2003
Summary
This study defines significant deviations in liquid drop shapes due to gravity, establishing Eotvos number limits. These limits help determine when simplified contact angle estimations are valid.
Area of Science:
- Fluid dynamics
- Surface science
- Physical chemistry
Background:
- Liquid drop shape on solid surfaces is influenced by surface tension and gravity.
- Spherical section assumption simplifies contact angle estimation but may be invalid.
- Gravity's effect becomes significant as surface tension decreases.
Purpose of the Study:
- To define significant deviations in liquid drop shape from spherical.
- To estimate dimensionless Eotvos number limits for significant deviation.
- To facilitate contact angle estimation by identifying when simplified models are applicable.
Main Methods:
- Numerical solution of the Laplace equation for drop shape.
- Using drop volume and wetted radius as constraints.
- Investigating varying interfacial tension and drop sizes.
Main Results:
- Eotvos number limits were estimated for a 1-degree contact angle deviation.
- Results are independent of density difference sign and drop size.
- Limiting Eotvos numbers are expressed as a function of the original contact angle.
Conclusions:
- Established Eotvos number limits provide criteria for using simplified spherical section assumption.
- These limits are crucial for accurate contact angle estimation.
- The findings aid in assessing the validity of shape-related analyses in fluid systems.