Weissenberg effect

In fluid dynamics, the Weissenberg effect is a phenomenon that occurs when a spinning rod is inserted into a solution of elastic liquid. Instead of being thrown outward, the solution is drawn towards the rod and rises up around it.^[1] This is a direct consequence of the normal stress that acts like a hoop stress around the rod. The effect is a common example of non-Newtonian fluid dynamics, which has been shown to occur for polystyrene.^[2] The effect is named after Karl Weissenberg who published about it in 1947.^[3]

Illustration of the Weissenberg effect on a 2% solution of high molecular weight polyacrylamide