Using a rectangular prism with square cross-section and an aspect ratio of two, the paper studies effect of the Moving Surface Boundary-layer Control (MSBC) on the fluid dynamics of a barge-like structure. The momentum injection was provided through two rotating cylinders forming vertical edges of the upstream square face. Wind tunnel results at a subcritical Reynolds number of 5~10~ are complemented by the tow-tank experiments. Results suggest significant effect of the MSBC on both pressure distribution as well as forces acting on the barge. In general, the momentum injection leads to a delay in the boundary-layer separation and hence a reduction in the pressure drag. For the present case, wind tunnel results showed a reduction in the drag coefficient of around 24%, while the tow-tank study suggested a decrease of as large as 28% for a Froude number of 0.18. It is important to point out that the MSBC is essentially a semi-passive process. The rotating elements are hollow cylinders and the power required in overcoming the bearing friction as well as fluid resistance is rather small. Results suggest that for an input of lW, there is at least SW reduction in power due to the decrease in drag. A brief video will accompany the presentation.
Ever since the introduction of the boundary -layer concept by Prandtl, there has been a constant challenge faced by scientists and engineers to minimize its adverse effects and control it to advantage. Methods such as suction, blowing, vortex generators, turbulence promoters, etc. have been investigated at length and employed in practice with a varying degree of success. A vast body of literature accumulated over years has been reviewed rather effectively by several authors including Lachmann (1961), Rosenhead (1966), Schlichting (1968), Chang (1970), and others.