Fuck Yeah Fluid Dynamics

Celebrating the physics of all that flows. Ask a question, submit a post idea or send an email. You can also follow FYFD on Twitter and Google+. FYFD is written by Nicole Sharp, PhD.

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Posts tagged "condensation"

This numerical simulation from NASA Goddard shows the motion of particulates in Earth’s atmosphere between August 2006 and April 2007. These aerosols come from various sources including smoke, soot, dust, and sea salt. As these fine particles move through atmosphere, they can have significant effects on weather as well as climate. For example, the particles serve as nucleation sites for the condensation and formation of rain drops. (Video credit: NASA Goddard SFC)

This stunning National Geographic photo contest winner shows an F-15 banking at an airshow and a array of great fluid dynamics. A vapor cloud has formed over the wings of the plane due to the acceleration of air over the top of the plane. The acceleration has dropped the local pressure enough that the moisture of the air condenses.  Some of this condensation has been caught by the wingtip vortices, highlighting those as well. Finally, the twin exhausts have a wake full of shock diamonds, formed by a series of shock waves and expansion fans that adjust the exhaust’s pressure to match that of the ambient atmosphere. (Photo credit: Darryl Skinner/National Geographic; via In Focus; submitted by jshoer)

When conditions are just right, the low pressure at the center of a wingtip vortex can drop the local temperature below the dew point, causing condensation to form. Here vortices are visible extending from the tips of the propellers in addition to the wingtip. Because of the spinning of the propeller and the forward motion of the airplane, the prop vortices extend backwards in a twisted spiral that will quickly break down into turbulence. The same behavior can be observed with helicopter blades. (Photo credit: benurs)

Under the right atmospheric conditions, condensation can form, even at low speeds, as moist air is accelerated over airplane wings. This acceleration causes a local drop in pressure and temperature, which can cause water vapor in the air to condense. The condensation can sometimes get pulled into the wingtip vortices shed off of the wings, tail, and ailerons of an aircraft, as in the video above, making the aerodynamics of the airplane visible to the naked eye.

This August 25th satellite image shows Hurricane Irene over the Bahamas and Florida. Hurricanes are fueled largely by the release of heat as warm water vapor in the rising air condenses. The hurricane requires a body of warm water to sustain the process, which is why hurricanes weaken drastically after they make landfall. Over open water, the heat released by condensation fuels higher winds, which lowers the pressure at the center of the system and helps increase the rate of evaporation near the ocean surface, providing additional warm vapor for future condensation. See more photos of Irene from space, along with video from the ISS#

Condensation clouds form around sections of Atlantis as STS-135—the final space shuttle flight—launches from Cape Canaveral this morning. These clouds, also called Prandtl-Glauert singularities or vapor cones, form at transonic speeds when air accelerates around the vehicle. The area just behind these shock waves experiences a drop in pressure and temperature that brings a localized portion of the flow below the dew point. Rapid condensation of the moisture in the air results. Miss the launch? Watch it here.