The surface velocity is not quite the same as the mean velocity. If you
want to work in terms of surface vel the appropriate formula is:
usurface=2.5 utau ln(30d/a).
You will find these formulae in any good textbook on free surface
hydraulics and also in my own book (Sea Bed Mechanics, Wiley, p36 - there
is a copy in the University Library). The formula for friction factor comes
directly from its definition.
Best wishes
John Sleath
To fix the heatkeeper figure I did this
latex figures
dvips -E -p 291 -l 291 ./figures.dvi -o ps/individual302/figure291.eps
date
Wed Oct 27 19:20:39 BST 2010
autoBib.pl bibliography.html > bib.html
cp bib.html ~/pubwww/withouthotair/