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Volkmar von Arnim

fields of research at MIT

Nano- and micro scale non-wetting behavior of ultra hydrophobic substrates

 


 
High speed videos of dynamic droplet behavior 
(You can download a free Quick Time movie player to visualize the movie links .

 

bouncing droplets
A droplet of approximately 1 mm diameter is released  and impacts the superhydrophobic surface at low Weber number. 
 avi 3.3 MByte
Watch the elastic rebound behavior!

avi 4.2 MByte
Watch the rebounds with coefficients of restitution of 0.9!


 
bouncing droplet #2

avi 400 kByte

A droplet of approximately 1.5 mm diameter is released and impacts the superhydrophobic surface at high Weber number. 

Watch the complex droplet oscillation behavior!

 

almost bouncing droplet 
avi 570 kByte A droplet of approximately 1 mm diameter is released 
and impacts the hydrophobic surface at low Weber number. 

Watch the large contact angle hysteresis, preventing the droplet from bouncing!


 

non bouncing droplet
avi 460 kByte
A droplet of approximately 1 mm diameter is released 
and impacts the hydrophobic surface at low Weber number. 

watch the large contact angle hysteresis which lets the droplet stick to the surface!



 
surprising effects of surface tension 
A water droplet of approx. 1 mm diameter impacts another resting spherical water droplet at low Weber number
avi 670 kByte

avi 480 kBytewatch the video!

 

watch the surprising behavior!


 
Droplet fusion
  avi 270 kByte

The fusion of droplets is inhibited, epecially for small spherical droplets, because the intermediate state with enlarged surface area is energetically unfavourable.