Lift Generation in Soft Porous Media

A red blood cell is about eight microns in diameter,
but it fits through capillary openings of only five
or six microns in diameter without showing any wear
and tear. It manages this tight squeeze about
100,000 times in its lifetime. How could there be so
little friction? A 70 kg human being can glide over
a compressed snow layer without sinking to the base,
however, when the motion is arrested, the skier
would sink to the base. Why is that? In fluid
mechanics it is highly unexpected for there to be a
dynamic similarity between the motions of objects
that differ in mass by many orders of magnitude. Yet
this is exactly what has been discovered in
comparing the motion of a red cell in a capillary,
the compression of fresh snow during skiing and the
passage of a train car over a track that has the
mechanical properties of a goose down pillow. These
diverse applications are unified in this book. The
book introduces a new concept that is of
extraordinarily broad interest and could have
important application in the design of soft porous
bearings with greatly increased lubrication
pressures and long life.