1. Postdoctoral Research Associate, Dept. of Civil Engineering, Univ. of Dundee, Dundee DD1 4HN, U.K. E-mail: a.j.s.cuthbertson@dundee.ac.uk
2. Professor of Fluid Mechanics, Dept. of Civil Engineering, Univ. of Dundee, Dundee DD1 4HN, U.K. E-mail: p.a.davies@dundee.ac.uk