Moving liquid droplets with inertia: Experiment, simulation, and theory

Moving liquid droplets with inertia: Experiment, simulation, and theory

Kim, H.

Westerweel, J. (promotor)

Mechanical, Maritime and Materials Engineering

Process and Energy

2013-02-05

This thesis is a work on a contact line instability at a finite Reynolds number, 0 < Re < O(100). This problem corresponds to an immersion droplet applied in a liquid- immersion lithography machine. We perform extensive works to understand this instability problem by means of experimental, numerical, and theoretical ways. First, in order to measure the 3D internal flow pattern, we perform 3D-3C velocimetry techniques, i.e. tomographic particle image velocimetry and 3D particle tracking velocimetry. Furthermore, we observe droplet shape changes by shadowgraphy. Second, based on these experimental results, we develop a modified three-dimensional lubrication model including inertial effects. In this model, the pressure is described as a combination of dynamic pressure effects and capillary pressure effects. By this extended model, we obtain an analytical solution describing the relationship between opening angles and receding angles. Additionally, we show a self-similar flow pattern near the dewetting contact lines. Last, a simplified numerical model is introduced for a liquid immersion droplet. For the numerical computation, we adopt a flat cylinder and apply a zero flux boundary condition at the gas-liquid interface. The numerical results are compared with measurement results and give a good agreement.

moving contact line
immersion droplet
tomographic particle image velocimetry
3D particle tracking velocimetry
modified lubrication theory
wetting and dewetting
zero-flux boundary condition model

https://doi.org/10.4233/uuid:a9188ceb-e1ff-4233-ae9b-58dd5853ab6d

Delft University of Technology

9789461861153

Institutional Repository

doctoral thesis

(c) 2013 Kim, H.