Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Hydrofoil Cavitation
A cavitation-induced bubbly sheet flows over the upper surface of a hydrofoil in the image above. Cavitation can occur when local pressure in a liquid drops below the vapor pressure, causing a cavity to form. Due to its angle of attack, water flowing over the upper surface of the hydrofoil is accelerated. The high flow…
Zesty Fireballs
Zesting the skin of a citrus fruit like oranges releases a spray of tiny oil droplets. Citrus oil has several volatile components, meaning that it evaporates quickly at room temperature. It is also a liquid with a relatively low flash point, meaning that only modest temperatures (~40-60 degrees Celsius) are needed to generate enough vapor to…
Shooting Droplets
This animation shows high-speed video of a polystyrene particle striking a falling water droplet. Under the right conditions, the particle rips through the droplet, stretching the water into a bell-shaped lamella extending from a thicker rim. When the particle detaches, surface tension rapidly collapses the lamella into a ring which destabilizes. Thin ligaments and droplets…
Phytoplankton Bloom
In satellite imagery the blue and green whorls of massive phytoplankton blooms stand out against the ocean backdrop. These microscopic organisms are part of a delicate predator-prey balance and can be very sensitive to nutrient concentrations and other environmental conditions. Their individual size is negligible, but in a bloom phytoplankton are numerous enough that they…
Bouncing with Liquids and Grains
Bouncing a ball partially filled with a liquid can create chaotic results when the motion of the ball, fluid, and vibration plate couple. The behavior of a grain-filled ball is a bit different, though. Large grains will tend to bounce with the same frequency as the ball, even across a range of vibration conditions. A…
Supernova Simulation
New research shows that supermassive first-generation stars may explode in supernovae without leaving behind remnants like black holes. The work is a result of modeling the life and death of stars 55,000 to 56,000 times more massive than our sun. When such stars reach the end of their lives, they become unstable due to relativistic…
Turbine Blade Separation
[original media no longer available] Maintaining consistent air flow along the contours of an object is key to aerodynamic efficiency. When air flow separates or forms a recirculation zone, the drag increases and efficiency drops. On wind turbine blades, flow often separates on the root end of the blade near its attachment point. This behavior…
Hovering
Designer Eleanor Lutz used high-speed video of five different flying species to create this graphic illustrating the curves swept out in their wingbeats. The curves are constructed from 15 points per wingbeat and are intended more as art than science, but they’re a fantastic visualization of several important concepts in flapping flight. For example, note…
Bardarbunga Eruption
I thought I was done with volcanoes for this week, but DJI’s aerial footage from Iceland’s Bardarbunga eruption is too fantastic not to share. The eruption is over a month old now and more than 25,000 earthquakes have been registered in Iceland since this eruption began. The lava field covers more than 46 square kilometers, and experts remain…
Undulatus Asperatus
This surrealistic timelapse doesn’t show an ocean in the sky. These are undulatus asperatus clouds rolling over Lincoln, Nebraska. Also known simply as asperatus, this cloud formation has been proposed as but not yet recognized as a distinctive cloud type. Their speed is much slower than shown in the animation, but the wave-like motion is…