The Weissenberg Effect

When a rod mounted in a hand drill is dipped into a liquid and rotated, for certain non-Newtonian fluids the liquid will climb the rod - sometimes to quite spectacular heights. Such rob climbing behaviour is referred to as the Weissenberg Effect. Shearing in the flow of the liquid concentrically around the rotating rod causes the component of the stress normal to the circular flow direction to become greater in magnitude compared to the two other mutually perpendicular components. This causes the fluid