r Maryami - Assistant professor, University of Sistan and Baluchestan
M H Shafiei Mayam - Assistant professor, University of Sistan and Baluchestan;
s Farahat - Assistant professor, University of Sistan and Baluchestan;
m JavadPour - Assistant professor, University of Sistan and Baluchestan;

This work focuses on studying the drag reduction due to the presence of micro-bubbles in a vertical Couette-Taylor system. The study was carried out numerically using a discrete phase model for a fully turbulent flow, which maximum Reω is up to 3000. Main flow is water and the airbubbles are injected constantly at the bottom of cylinder and rise through the flow. At the first stepthe bubbles distribution or bubbles pattern through the flow, that is acquired using numericalmethod, shows a good agreement with those found via the experimental data for all Reynoldsnumbers. The effect of injected air with constant flow rate on the drag reduction was studied usingvariation of friction coefficient which was calculated by the variation of shear stress on thecylinder surface. The results confirmed about 25% of drag reduction when micro bubbles wereinjected in the system. This reduction was the effect of the bubbles on the density of fluid and transformed momentum. Moreover, the acquired numerical results were in good agreement to those found in the previous experimental works

Micro bubbles, Friction drag, Drag reduction, Couette-Taylor system, Discrete phase model