The Physics of Microdroplets, Chapter 5

This page contains Evolver datafiles for Chapter 5 images. The data files contain evolution scripts (always named "gogo") and scripts for producing EPS files for the book images (always named "run").

The image scripts set the viewing angle with the "view_matrix := ..." command. The particular view matrix used was generated by moving the surface by mouse and then printing out the view matrix with the "print view_matrix" command, and cutting and pasting the result into the command.

Fig. 5-6 Wetting drop between nonparallel planes moving toward narrow end.
Fig. 5-7 Flattened drop moving towards wider end.
Fig. 5-8 Drop moving toward dihedral.
Fig. 5-9 Different contact angles, drop moving toward wider end.
Fig. 5-13 Drop in 90 degree wedge.
Fig. 5-16 Drop evolving to filament.
Fig. 5-18 Drop in hydrophobic wedge.
Fig. 5-19 Filaments in micro-beaker.
Fig. 5-21 Drop in corner.
Fig. 5-22 Drop in wetting and nonwetting corners.

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Fig. 5-6 Wetting drop between nonparallel planes moving towards narrow end.

This model has level-set constraints for the top and bottom planes, with explicit contact facets, for showing the contact area in the images. The black bar is just a marker facet for reference. There is no equilibrium here, just a movement to the right towards lower energy. Beware that while Evolver may appear to simulate dynamical processes, it does not in fact do so.

Datafile: Fig_5_6.fe

Fig. 5-7 Flattened drop moving towards wider end.

Here the planes are hydrophobic enough that the liquid does not want to wet the dihedral angle, and the drop starts in a position where it is flatter than spherical. It moves towards the wider end until it reaches its minimum energy position of a sphere.

Datafile: Fig_5_7.fe

Fig. 5-8 Drop moving toward dihedral.

Here the planes are hydrophobic, but slightly, so the liquid wants to wet the dihedral angle. There is no equilibrium reached here, just continuous motion to the right.

Datafile: Fig_5_8.fe

Fig. 5-9 Flattened drop moving towards wider end.

Different hydrophobic contact angles, hydrophobic enough that the liquid does not want to wet the dihedral angle, and the drop starts in a position where it is flatter than spherical. It moves towards the wider end until it reaches its minimum energy position of a sphere.

Datafile: Fig_5_9.fe

Fig. 5-13 Drop in corner.

	Droplet wetting the dihedral of a 90 degree wedge, i.e. the base of a wall. The contact angles are 90 degrees on the wall and 50 degrees on the floor. With a small drop, gravity has little effect and the equilibrium shape is nearly spherical. Datafile: Fig_5_13_a.fe
	Gravity flattens a larger drop. it on the right. Gravity is implemented in the datafile by giving the body a "density", and defining the "gravity_constant" in the top of the datafile. Datafile: Fig_5_13_b.fe

Fig. 5-16 Drop evolving to filament.

	Initial shape of drop at base of wall. Datafile: Fig_5_16_a.fe
	Evolving towards a filament, contact angles each 40 degrees. Datafile: Fig_5_16_b.fe
	Stable drop contact angles 80 degrees. Datafile: Fig_5_16_c.fe

Fig. 5-18 Drop in hydrophobic wedge.

Starting configuration, with contact angles of 110 degrees on wall and floor. Evolves to still wet the corner.

Datafile: Fig_5_18_ab.fe

Contact angles of 150 degrees on wall and floors, so does not wet the corner. The initial shape here started off with a tunnel in the corner, so no fancy script was needed to create the tunnel from the starting configuration shown above.

Datafile: Fig_5_18_c.fe

Fig. 5-19 Filaments in corner of micro-beaker.

The left image shows a mildly hydrophilic contact angle of 80 degrees, where all is well-behaved. The right shows a contact angle of 30 degrees, growing filaments up the corners.

Datafile: Fig_5_19.fe

Fig. 5-21 Droplet in corner.

Here the wall and floor have different contact angles, 45 degrees and 25 degrees. Same datafile as 5-16, just contact angles changed.

Datafile: Fig_5_21_a.fe, Fig_5_21_b.fe

Different hydrophobic angles, 160 degrees and 140 degrees. Same datafile as 5-18c, with different contact angles.

Datafile: Fig_5_21_c.fe

Fig. 5-22 Droplet in corner with wetting and non-wetting.

Left, contact angles 130 degrees and 60 degrees, so drop wets both wall and floor. Right, contact angles 130 degrees and 30 degrees, so drop goes entirely to floor. The right image is the same datafile as the left, but to keep the wall contact line from dropping below the floor, a one-sided constraint was imposed on the wall contact line.

Datafile: Fig_5_22.fe

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