Rod-climbing effect in Newtonian fluids.
When a rotating rod is brought into a polymer melt or concentrated polymer solution, the meniscus climbs the rod. This spectacular rod climbing is due to the normal stresses present in the polymer fluid and is thus a purely non-Newtonian effect. A similar rod climbing of an interface between two fluids has therefore been taken as a signature that one of the fluids exhibits normal stress effects. We show here, however, that the effect can occur with simple Newtonian fluids: it occurs when a Taylor-Couette instability happens in the less viscous of the two liquids but not in the more viscous one.
Bonn
Daniel
D
Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris cedex 05, France. bonn@lps.ens.fr
Kobylko
Mathias
M
Bohn
Steffen
S
Meunier
Jacques
J
Morozov
Alexander
A
van Saarloos
Wim
W