Development and Implementation of a Low-Cost 3D-Printed Rotational Viscometer for Rheology and Fluid Mechanics Education

Viscosity measurement is a fundamental concept in fluid mechanics and is essential for engineering education, yet the high cost of commercial rotational viscometers limits hands-on learning opportunities. We present the development and implementation of a Low-Cost Rotational Viscometer (LC-RV) utilizing 3D-printed components and off-the-shelf materials for educational purposes. The LC-RV replaces expensive rotary torque sensors with a linear force sensor mounted on the stationary cup, capturing shear-induced forces to calculate the rheological properties. We validated the LC-RV’s ability to consistently measure viscosity over 3 orders of magnitude by testing Newtonian fluids like mineral oil and glycerol solutions at various concentrations and shear rates. Additionally, we demonstrated that it could analyze non-Newtonian fluids like soap by capturing the changing viscosity as a function of shear rate. The LC-RV was implemented in an undergraduate fluid mechanics course, providing students with practical hands-on experience in viscosity measurement. A cognitive assessment based on thematic analysis of student responses indicated that the majority effectively grasped key concepts in viscosity and rheology, with many demonstrating high levels of cognitive engagement. We provide the design files, program codes, and assembly instructions, enabling others to implement, expand, and adapt LC-RV for diverse pedagogical and research applications beyond classroom demonstrations.