Pictures, Animations Etc

  • An owl in flight, with periodic almost rigid flapping.
  • Even behind a rigid wing, we know there are complex vortex structures like this and that.
  • Shed vorticity can be used to ease formation flight and fish schooling.
  • A photographic sequence of an insect in flight, modelled by an animated gif (Windows systems often have trouble with this.)
  • The wake behind a flying insect is at intermediate Reynolds number, and quite complex.
  • Swimming is quite similar to flying. This shark is a high-Re swimmer and moves by flapping its caudal (tail) fin, whereas this fish sends waves down its dorsal fin. This bizarre "red Indian fish" is practically all dorsal fin.
  • Backwards-travelling waves are a frequent propulsion mechanism, as they work both at high and low Reynolds numbers. This worm swims in the same direction as the travelling wave.
  • Many bacteria move by sending travelling waves down long appendices called flagellae. This one swims with a low-Re sort of breast stroke.
  • Other organisms have many external flagellae or cilia. Each individually performs a breaststroke, but by varying the phase with the neighbours an effective travelling wave propels the organism. Cilia also occur inside the body to propel mucus down passages. This frog uses cilia to stir rather than propel fluid.
  • The upwards swimming of large numbers of organisms heavier than the surrounding fluid can lead to Bioconvection. Here are three illustrations of bioconvection patterns: Stripes or rolls can break down into more hexagonal patterns. Here are two more
  • Haemodynamics involves time-dependent flow down the arterial tree,a complex network of pipes.
  • A typical pressure and pressure gradient from an elderly human, is observed to.
  • Steepen as it travels down the arterial tree
  • The aortic arch, curves 3-dimensionally
  • is clear from this cast of a canine aorta
  • The umbilical cord contains highly helical artery and veins (this image is copyrighted)
  • The complex particle patterns near a bifurcation can be seen on this animation from David Steinman of Toronto
  • Here is a fatty streak in an arterial wall, the first stage in the development of atheroma and atherosclerosis
  • This slide from Caro et al illustrates the strong correlation between wall shear stress distributions and regions of atherosclerotic lesion formation.
  • This ultrasound picture illustrates how constricted the arteries can become in time. The arrow points to a plaque region which could break off and cause a heart attack.
  • This schematic of a bypass graft indicates the reblocking ("neointimal hyperplasia") which can occur. Some bypass geometries are better than others.
  • And finally, a message from our sponsor. In Latin.

    Many thanks to a number of people in producing these images, including Kim Parker, Colin Caro, Tim Pedley, David Steinman, Charlie Ellington, Steve Childress, Ed Spiegel, Nick Hill and others I may have forgotten to mention but to whom I am no less grateful.

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