Reshaping recoiling drops

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Reducing the contact time of a bouncing drop
We investigate how surface texture can modify the shape of a drop as it impacts a nonwetting surface.  In particular, we demonstrate that certain macrotextures can lead to a phenomenon in which the center of the drop assists in the recoil.  When these textures are incorporated on non-wetting surfaces, they can significantly reduce the time that the drop is in contact with the surface, effectively keeping the surface drier. 

Press Coverage:  New York TimesBoston Globe, Phys Org.


Leidenfrost

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Leidenfrost effect on textured surfacesWe are interested in the effects of surface texture on how hot a surface must be to float a drop on the it’s own vapor.Press Coverage:  Newswise

Bubble ring from bursting bubble Rupturing bubbles and thin filmsSmall bubbles are important in health, the environment, and in industry in part because the rupture of these bubbles can transfer small droplets into the atmosphere. We are researching how the rupture of large bubbles can create a ring of these smaller bubbles – a phenomenon that can be easily observed in the kitchen sink. Our results have linked these smaller, daughter bubbles to the shape of the larger bubble as it collapses. Movies

Related Publications

Press Coverage:
NPR (radio and video), New York TimesBBCBoston Globe
Highlighted in Physics Today/Backscatter


Splashing controlled
with tangential velocity
Drop Impact and splashingDrops falling on to inclined or moving surface experience a tangential velocity at impact. The tangetial velocity of the surface relative to the drop can trigger or inhibit a splash. In addition to describing asymmetries from tangential velocity, our study provides more general insight into the fundamental mechanisms responsible for splashing on dry, smooth substrates.Related Publications

Geometric noncoalescence Electrocoalescence of conical dropsOppositely charged liquid drops deform into cones as they contact. We are interested in their deformation, as well as the subsequenct behavior after contact. These conical drops fail to coalesce above a critical cone angle, a phenomenon we believe is due to mainly to local geometery. MovieRelated Publications

Press Coverage:
HarvardScienceNew ScientistScienceNOWPhysics World


Early spreading of dropletspartial spreading The initial dynamics of partial wettingWhen a liquid drop contacts a wettable surface, the liquid spreads over the solid to minimize the total surface energy.  For perfectly wetting systems, the first moments of spreading are inertially dominated. We demonstrate that even in the presence of a contact line, the initial wetting is dominated by inertia rather than viscosity.  Additionally, we find that the spreading radius follows a power-law scaling in time where the exponent depends on the equilibrium contact angle.Related Publications