Abstract
Experiments were carried out to make sure that the air exist in the fine many grooves on the highly water repellent-wall when tap water flow on the wall. It was cleared that the air exist in fine grooves when the wall was covered by water. However, the fine grooves were filled with the solution in the case of Ethoquad O/12 solutions that the drag reduction does not occur. It is seen by the flow visualization results that the difference lies between the flows behavior of laminar and turbulent flows near the wall for the shape the interface between the groove edge and liquid.
