Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 52 4 2019 01 16 The Drag Coefficient Prediction of a Rising Bubble through a Non-Newtonian Fluid The Drag Coefficient Prediction of a Rising Bubble through a Non-Newtonian Fluid 863 880 3237 10.22060/mej.2019.14927.5977 FA Safoora Karimi Department of Chemical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Mojtaba Shafiee Department of Chemical Engineering, Faculty of Chemical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Anna Abiri Department of Chemical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Farzad Ghadam Department of Mechanical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Journal Article 2018 09 03 In the present research, the drag coefficient of a single bubble rising in the non-Newtonian fluid has been investigated. Polyacrylamide solutions were selected with different concentrations as a Non-Newtonian fluid. As known, these solutions have viscoelastic properties which strongly influence the drag coefficient. The experiments have been done with different nozzle diameters, for three types of gas (Air, and ) at different injection flow rates. Hence, the results are more comprehensive than in previous studies. A comparison between the obtained results and the equations in other studies showed that none of these relationships can predict the drag coefficient of a bubble rising in a non-Newtonian fluid with a viscoelastic property. Therefore, two new correlations have been presented to predict the drag coefficient based on Reynolds, Archimedes and Eötvös dimensionless number by dimensional analysis. The first equation which obtained directly from the dimensional analysis was simpler than the second equation. The average error of the first equation was 3.26%, while, the average prediction error of the second equation was about 1.7%, which is more complex in terms of formulation. In addition, new equations for predicting terminal velocities and the behavior of bubble rising in a non-Newtonian viscoelastic fluid are presented. In the present research, the drag coefficient of a single bubble rising in the non-Newtonian fluid has been investigated. Polyacrylamide solutions were selected with different concentrations as a Non-Newtonian fluid. As known, these solutions have viscoelastic properties which strongly influence the drag coefficient. The experiments have been done with different nozzle diameters, for three types of gas (Air, and ) at different injection flow rates. Hence, the results are more comprehensive than in previous studies. A comparison between the obtained results and the equations in other studies showed that none of these relationships can predict the drag coefficient of a bubble rising in a non-Newtonian fluid with a viscoelastic property. Therefore, two new correlations have been presented to predict the drag coefficient based on Reynolds, Archimedes and Eötvös dimensionless number by dimensional analysis. The first equation which obtained directly from the dimensional analysis was simpler than the second equation. The average error of the first equation was 3.26%, while, the average prediction error of the second equation was about 1.7%, which is more complex in terms of formulation. In addition, new equations for predicting terminal velocities and the behavior of bubble rising in a non-Newtonian viscoelastic fluid are presented. https://mej.aut.ac.ir/article_3237_544a4f59f691574154a60b8539ebf914.pdf