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Published on: March 11, 2020
Thermocapillary motion of a liquid drop on a horizontal solid surface.
Vikram Pratap1, Nadjoua Moumen, R Shankar Subramanian
1Department of Chemical Engineering and Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699-5705, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|April 11, 2008
Summary
This study investigates decane drop motion on poly(dimethylsiloxane) (PDMS)-coated surfaces under a temperature gradient. A theoretical model accurately predicts velocity scaling with drop size and temperature gradient, despite lower experimental velocities.
Area of Science:
- Fluid dynamics
- Surface science
- Materials science
Background:
- Thermocapillary effects drive fluid motion in response to temperature gradients.
- Understanding drop dynamics on solid surfaces is crucial for applications in microfluidics and material processing.
- Poly(dimethylsiloxane) (PDMS) is a widely used material for surface coatings due to its unique properties.
Purpose of the Study:
- To experimentally investigate the thermocapillary motion of decane drops on PDMS-coated surfaces.
- To develop and validate a theoretical model for drop velocity under a temperature gradient.
- To analyze the influence of drop size, temperature gradient, and contact angle hysteresis on drop motion.
Main Methods:
- Experimental study of decane drop movement on PDMS-coated glass surfaces with controlled temperature gradients.
- Application of lubrication approximation for theoretical modeling of thermocapillary drop motion.
- Systematic variation of drop size and temperature gradient to compare experimental and theoretical results.
Main Results:
- The theoretical model accurately predicts the scaling of drop velocity with drop size and temperature gradient.
- Experimental velocities were consistently lower than theoretical predictions.
- Contact angle hysteresis had a minimal effect on critical drop size, which was independent of the temperature gradient.
- Drop deformation and contact line behavior were correlated with temperature difference and capillary number.
Conclusions:
- The lubrication approximation provides a valid framework for understanding thermocapillary drop motion on solid surfaces.
- While the model captures scaling laws, further refinements are needed to match absolute velocity measurements.
- The minimal influence of contact angle hysteresis simplifies the understanding of critical drop motion conditions.
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