Paper Number
PO128 

Session
Poster Session

Title
Rod-climbing rheometer: Measuring the normal stresses

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

1. More, Rishabh V. (MIT, Mechanical Engineering)
2. McKinley, Gareth H. (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Rishabh V. More and Gareth H. McKinley
Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142

Speaker / Presenter 
More, Rishabh V.

Keywords
experimental methods; rheometry techniques

Text of Abstract
The rod-climbing or the “Weissenberg” effect, where the free surface of a fluid climbs a thin rotating rod, is a popular and convincing experiment demonstrating the elasticity in polymeric fluids. The interface shape and the climbing height are generally dependent on the rate of rotation, as well as the fluid elasticity, normal stresses, surface tension, and inertia. However, by solving the equations of motion in the slow rotation rate limit for a second-order fluid, a mathematical relationship between the interface deflection and the fluid material functions, especially normal stresses, emerges. This establishes the rod-climbing experiment as a prime candidate for measuring normal stresses in polymeric fluids in conditions that are often not in the sensitivity ranges of commercial rheometers. To this end, in this poster, we illustrate the capabilities of the rod-climbing experiment as a rheometer to measure the normal stresses in polymeric fluids accurately.