Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Jets from Lasers
Laser-induced forward transfer (LIFT) is an industrial printing technique where a laser pulse aimed at a thin layer of ink creates a tiny jet that deposits the ink on a surface. In practice, the technique is plagued with reproducibility issues, in part because it’s difficult to produce only a single cavitation bubble when aiming a laser at the liquid…
Avoiding Droplet Contact
Cold rain splashing on airplane wings can freeze in instants. To prevent that, researchers look for ways to minimize the time and area of contact a drop has. Hydrophobic coatings and textures can do some of the work, but they are easily damaged and don’t always work well when it comes to freezing. The new technique shown here uses ring-shaped “waterbowls”…
Understanding Meteorite Geometry
Back in February 2013, the skies over Russia were lit by the fall and explosion of a large meteor. The scavenger hunt for meteorite pieces that followed turned up lots of conically-shaped chunks of rock, consistent with other meteors. Why do so many meteorites end up in this shape? There are a couple factors influencing it.…
Phytoplankton Swirls
A winter bloom of phytoplankton appears as green and teal swirls in this false-color satellite image of the Gulf of Aden. Although phytoplankton can be an important food source for fish and other marine animals, in recent years we’ve observed more frequent toxic blooms. Currently, physical sampling of the phytoplankton is necessary to determine what type they…
Seeing the Song
We can’t always see the flows around us, but that doesn’t mean they’re not there. Audobon Photography Award winner Kathrin Swaboda waited for a cold morning to catch this spectacular photo of a red-winged blackbird’s song. In the morning chill, moisture from the bird’s breath condensed inside the vortex rings it emitted, giving us a…
Catching Fire
Citrus fruits like oranges house tiny pockets of oil in their peels. When squeezed, the oils jet out in tiny micro-jets that are about the width of a human hair. Despite their small size, the jets reach speeds of about 30 m/s and quickly break into a stream of droplets. When exposed to the flame…
Reducing the Force of Water Entry
As anyone who’s jumped off the high board can tell you, hitting the water involves a lot of force. That’s because any solid object entering the water has to accelerate water out of its way. This is why gannets and other diving birds streamline themselves before entering the water. But even for non-streamlined objects, like a sphere,…
Doing the Wave
Not everything that behaves like a fluid is a liquid or a gas. In particular, groups of organisms can behave in a collective manner that is remarkably flow-like. From schools of fish to fire-ant rafts, nature is full of examples of groups with fluid-like properties. One of the most mesmerizing examples are these giant honeybee colonies, which essentially do “the…
Striped Clouds
Living near the Rocky Mountains, it’s not unusual to look up and find the sky striped with lines of clouds. Such wave clouds are often formed on the lee side of mountains and other topography. But even in the flattest plains, you can find clouds like these at times. That’s because the internal waves necessary to create the clouds…
Underwater Optical Illusions
On a hot day, it’s not unusual to catch a glimpse of a shimmering optical illusion over a hot road, but you probably wouldn’t expect to see the same thing 2,000 meters under the ocean. Yet that’s exactly what a team of scientists saw through the cameras of their unmanned submersible as it explored hydrothermal vents deep…