Drainage induced convection rolls in foams - I. Convective bubble motion in a tilted tube S. J. Cox, M. D. Alonso, D. Weaire and S. Hutzler Eur. Phys. J. E, 19 1 (2006) 17-22 Published online: 17 January 2006 DOI: 10.1140/epje/e2006-00006-7