Interfacial phenomenon ofa single waterdroplet moving alongaglass surface

Meng Fan¹

¹  redmill@163.com Beijing, 100081, China

When a single water droplet moves along a glasswindow surface at a certain speed, what will happen? This short letter gives adescription of my observation about it. When water droplet moves forward, two stagesare  clearly observed :firstly, it splitsinto two parts, secondly, the separated part explodes  into small pieces in almost all directions atthe end of motion.

I. INTRODUCTION:

         Theobservation was accomplished in a journey by Chinese high-speed train, it was arainy day, the speed of the train is about 300 kilometer per hour. The rain dropswere adhered to the train window, then, it was moving in the reverse directionof the train, the velocity of the rain droplet relative to the train can’t beestimated by eyes, it doesn’t seems fast.

A.    Rain droplet motion on the glass surface and thephenomenon

The initial diameter of the raindroplet is about 3mm. When it moves along the glass surface, stage 1:the raindroplet gets smaller and smaller, the critical diameter is about 1.5mm then itsplits into two parts, the size of two parts are observed almost the same with eyes.Afterwards, one of the splited part keeps moving forward and gets smaller and smaller,the critical diameter is about 0.5mm, it explodes into pieces in almost alldirections at the end of the motion. The whole process is shown in FIG.1.

FIG. 1.  The entire process of a rain droplet moves along the glass surface. Two stages, split and explosion are observed

II. CONCLUSION:

When a single water droplet moves along the glass surface at a certainspeed, two clear stages: split into two parts and explosion are clearly observed.It can be easily observed and simply repeated by on board a high-speed train ina rainy day. This interfacial phenomenon may be potentially employed innano-manufactory for sputtering or to be avoided for the adverse influences inrelated fields.