Abstract: When a test tube is tilted, the settling rate of suspended particles is faster than that when the test tube is vertical. This is known as Boycott effect which has been subject to various theoretical explanations. In this study, Boycott effect is experimentally investigated with particle size, test tube tilt angle and particle density as variables. Liang-kai Huang′s fuzzy threshold method is used to accurately determine the settling rate from images obtained during experiments. The Krieger-Dougherty model is used to modify the traditional PNK theory of viscosity coefficient in the theoretical analysis. The results from the experiment are in good agreement with the modified theory.

Key words: Boycott effect, PNK theory, fluid mechanics