Drag coefficient and relative velocity in bubbly, droplet or particulate flows

Abstract Drag coefficient and relative motion correlations for dispersed two‐phase flows of bubbles, drops, and particles were developed from simple similarity criteria and a mixture viscosity model. The results are compared with a number of experimental data, and satisfactory agreements are obtained at wide ranges of the particle concentration and Reynolds number. Characteristics differences between fluid particle systems and solid particle systems at higher Reynolds numbers or at higher concentration regimes were successfully predicted by the model. Results showed that the drag law in various dispersed two‐phase flows could be put on a general and unified base by the present method.