Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
A belated reply: for trains, raising the bottom brings little benefits. Trains are too long and their underside has too many aerodynamically disturbing elements (bogies, inter-car transitions, brake equipment etc.) for a boundary layer flow below them; instead, there is a turbulent annular flow. What can be done is reducing the turbulence, and that is done the opposite way: with skirts and covers bringing the bottom closer to the rail. I find Chinese research saw much potential in this (although their percentage compőarisons are meaningless without specifying what are compared).

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Wed Jul 13th, 2011 at 10:13:01 AM EST
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