Effect of flexible fiber-flocking surface with grooves on drag reduction

Abstract

We investigated the influence of the wall surface properties on the drag reduction from the viewpoint of the flexibility of the fiber. The flow rate and pressure loss were measured for the water flows in a rectangular channel with an aspect ratio of ten having home-made fiber-flocking surfaces on the upper and lower walls. The test surfaces employed were smooth surface and two fiber-flocking surfaces with different groove heights. We additionally investigated the influence of the fiber height on the velocity profile by using LDV (Laser Doppler Velocimetry) measurement.