Applicability of Stokes method for measuring viscosity of mixtures with concentration gradient

• Main Authors: César Medina, Patricio Alastuey, Ana Clelia Gómez Marigliano
• Format: Article
• Language: Spanish
• Published: Universidade Federal de Santa Catarina (UFSC) 2017-12-01
• Series: Caderno Brasileiro de Ensino de Física
• Subjects: stokes; mezclas; gradiente de concentración; cálculo numérico
• Online Access: https://periodicos.ufsc.br/index.php/fisica/article/view/49958

After measuring density and viscosity of a mixture of glycerin and water contained in a vertical pipe, a variation of these properties according to depth is observed. These gradients are typical of non-equilibrium states related to the lower density of water and the fact that relatively long times are necessary to achieve homogeneity. In the same pipe, the falling velocity of five little spheres is measured as a function of depth, and then a numerical fit is performed which agrees very well with experimental data. Based on the generalization of these results, the applicability of Stokes method is discussed for measuring viscosity of mixtures with a concentration gradient.