The fuzzy interface of a drop

Dynamic contact angle of dilute polymer solution drops impacting on a hydrophobic surface

“…Recently, advanced techniques based on the local edge contour and on the image intensity gradient analysis were proposed [37,38]; unlike edge fitting approaches, these techniques are less sensitive to the image resolution. A simpler method, and the one used in the present work, is to approximate the local tangent with a line interpolating the three-phase-point and the nearest point of intersection between the drop contour and a horizontal line parallel to the baseline (i.e., a secant), as shown schematically in Fig.…”