Table of Contents
ISRN Mechanical Engineering
Volume 2011, Article ID 405701, 9 pages
Research Article

Boundary Layer Mixture Model for a Microbubble Drag Reduction Technique

Department of Engineering Science and Ocean Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10660, Taiwan

Received 8 April 2011; Accepted 20 May 2011

Academic Editors: A. E. Huespe and B. Yu

Copyright © 2011 Jing-Fa Tsai and Chi-Chuan Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The boundary mixture model is derived to predict the performance of the microbubble drag reduction technique for a flat plate. The flat plate with a porous material microbubble injecting system and resistance-measuring system are set up to measure the frictional resistance of the flat plate without and with injected microbubbles. The tests are conducted in a water tunnel and a towing tank. The test results show that the boundary mixture model predicts the drag reduction well for the flat plate when testing with injected microbubbles in the water tunnel. However, the boundary mixture model overestimates the drag reduction effect for the flat plate tested in the towing tank. The possible mechanism for the overestimation of drag reduction effect in the towing tank may be due to the different behaviors of microbubbles in the velocity gradient of boundary layer.