Numerical Simulation of Rod-Climbing Effect in Newtonian Fluids

This paper discusses about the onset of instabilities and rod climbing effect due to rotation of inner cylinder in Taylor Couette flow with two immiscible Newtonian fluids. The rod climbing effect, also known as Weissenberg effect, occurs in non-Newtonian fluids due to imbalance in normal stresses which pull the liquid inwards and make it climb. In two immiscible Newtonian fluids it occurs due to the onset of flow instabilities causing Taylor vortices in less viscous fluid (bottom fluid) which makes the interface to climb. Two-dimensional numerical simulations have been performed for a cylinder of 55 mm diameter and 60 mm height (30 mm by water & 30 mm of silicon oil) by using the Volume of Fluid method (VoF) in FLUENT. The initial volume fraction of water is patched into the lower half domain containing water. The initial swirl velocity is patched for the whole domain. For higher values of rotational speed the rod climbing effect was observed with upper fluid as silicon oil (μ = 300 mPas) and bottom fluid as water (μ = 1 mPas).