  Our experiments on the rod-climbing effect with an oil-coated rod revealed
two key differences in the rod-climbing phenomena compared to a bare rod. On
one hand, an enhancement in magnitude of climbing height for any particular
value of rod rotation speed and second, a decrease in threshold rod rotation
speed required for the appearance of the rod-climbing effect were observed.
Observed phenomena is explained by considering the contact line behavior at the
rod-fluid interface. Transient evolution of meniscus at the rod-fluid interface
revealed that the three-phase contact line was pinned for a bare rod and
de-pinned for an oil-coated rod. We modelled the subject fluid as a Giesekus
fluid to predict the climbing height. The differences in the contact line
behaviour were incorporated via the contact angle at the rod-fluid interface as
a boundary condition. An agreement was found between the observed and predicted
climbing height establishing that contact line behaviour may modulate
rod-climbing effect.
