Advances in Falling-Cylinder Viscometry: A Comprehensive Review

This paper focuses on falling-cylinder viscometry, a commonly used method for measuring viscosity due to its simplicity and versatility. The review explores the development of falling-cylinder viscometers, with an emphasis on their adaptability to high-pressure environment. The theoretical foundation for an ideal falling cylinder in a fluid within a rigid tube is discussed, addressing limitations arising from geometry, eccentricity, non-verticality, and entrance/exit effects. Critical Reynolds number and transient regime, are also examined. Practical aspects, including sinker design, working equations, calibration, as well as temperature and pressure influences on the constant apparatus, are discussed. By critically assessing these aspects, this review provides insights and recommendations for the effective application of falling-cylinder viscometry in both scientific and industrial contexts.