Abstract
The characteristics of drag coefficient of a vertical surface piercing cylinder in inundation flow are studied. The drag forces acting on the test cylinders in inundation flow of open channel were measured by using a multi component load cell in steady and unsteady flow were measured. The pressure distributions around the test cylinder were measured by using static-pressure measurement in steady flow. The time variation of typical principal velocity and water depth of coming inundation flow were also measured exactly by using a Laser Doppler anemometer and wave gages. The drag coefficient of the test cylinders decreases with increase of Froude number of uniform flow. The decrease of Cd with increase of instantaneous Froude number of coming flow is also appeared in unsteady flow like a dam braking flow. These phenomena may be due to the decrease of water surface depth appearing in wake of the test cylinder.
