Figure 3
From: Curvature-driven bubbles or droplets on the spiral surface
Free energy of a bubble on the spiral.
(a) The dimensionless energy versus dimensionless distance of bubble. The solid line is the analytical free energy curve in 2D for a bubble on the concave side of PMMA Archimedes spiral, and the other lines are the dimensionless free energy curves in all conditions on the Archimedean spiral in 3D. The Young’s contact angle of the bubble on PMMA and PE are selected as θY = 87.8° and θY = 93.1°, respectively. Insets are the simulated pictures of a bubble on the concave side and convex side. (b) The dimensionless driving force versus the dimensionless distance of the bubble from the spiral center. (c) The dimensionless driving force versus the dimensionless distance for different contact angles. The three groups, i.e., lines 1 & 6, lines 2 & 5, and lines 3 & 4 correspond to the case that θY = 60°, 90° and 120°, respectively. Solid lines 1, 2, 3, and dashed lines 4, 5 6 correspond to the concave side and convex side, respectively. (d) The free energy curves of the bubble on a logarithmic spiral with θY = 60° in 3D. Insets are the simulated pictures of a bubble on the concave and convex side of the spiral.
