Freed-Brown Julian
Department of Physics, The James Franck Institute, University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA.
Soft Matter. 2014 Dec 21;10(47):9506-10. doi: 10.1039/c4sm02133a. Epub 2014 Oct 28.
We present a framework for calculating the surface density profile of a stain deposited by a drop with a receding contact line. Unlike a pinned drop, a receding drop pushes fluid towards its interior, continuously deposits mass across its substrate as it evaporates, and does not produce the usual "coffee ring." For a thin, circular drop with a uniform evaporation rate, we find the surface density of the stain goes as η(r) ∝ ((r/a0)(-1/2)-r/a0), where r is the radius from the drop center and a0 is the initial outer radius. Under these conditions, the deposited stain has a mountain-like morphology. Our framework can easily be extended to investigate new stain morphologies left by drying drops.
我们提出了一个用于计算具有后退接触线的液滴所沉积污渍表面密度分布的框架。与固定液滴不同，后退液滴会将流体推向其内部，在蒸发过程中持续在其基底上沉积质量，并且不会产生常见的“咖啡环”。对于具有均匀蒸发速率的薄圆形液滴，我们发现污渍的表面密度与η(r) ∝ ((r/a0)(-1/2)-r/a0)成正比，其中r是从液滴中心起的半径，a0是初始外半径。在这些条件下，沉积的污渍具有类似山峰的形态。我们的框架可以很容易地扩展，以研究干燥液滴留下的新污渍形态。
