via [NASA Earth Observatory]
Full resolution can be found on wikimedia.
One can notice the depth of the ocean floor, on a global scale, ranges between -2000 and -6000 meters. In some regions though like the Pacific exceed this range and reach 11 kilometers below the sea surface. One such region is the deepest point on Earth, the Mariana trench as shown below followed by a map for a perspective of its location.
Credits: The SRTM dataset used was provided by IFREMER.
The Photograph shown is the raw image with no alterations. The image depicts a flat plate wing, which is simultaneously pitching and translating rapidly over a short distance through water at a Reynolds number of 10,000. This work is targeted towards understanding the aerodynamics of small insects with an intended application for Micro-Air Vehicles. The vortices are visualised by injecting a dye composed of milk and water. The milk has good reflective properties and is neutrally buoyant so follows the real flow faithfully. The inspiration for using milk came while pouring milk into a cup of tea at breakfast one morning! The photograph was taken by myself using a Nikon D7000 digital SLR camera, with the shutter speed and ISO adjusted to maximise the light entering the camera and allow the vortex structures to have a high contrast against the background. There are reflections of the vortex structures on the surface of the wing and some air bubbles are also visible on the dye injection needle on the wing’s surface.
In a previous post I shared a video on mixing and unmixing of fluids. This time I share with you an image I took of my coffee. With some milk fluid dynamics created amazing vortices. Following it is an animation of the time evolution of the vortices.