Comparison of Kinematics of Horseshoe Vortex at a Flat Plate and Different Shaped Piers

This paper presents an experimental investigation on the kinematics of horseshoe vortex around a flat plate. In order to have a comparative study, the velocity measurements within clear water equilibrium scour hole at circular, square, and equilateral triangular piers of sides equaling the width of the flat plate are also taken by an acoustic Doppler velocimeter. The contours and spatial distributions of the time- averaged (mean) velocities, turbulence intensities and turbulent kinetic degrees nergy at different azimuthal planes (0 degrees that is at the upstream axis of symmetry, 4 5, and 90 degrees) were deduced. Velocity vector plots of the flow field at azimuthal planes were used to show further flow features. The vorticity and circulation of the horseshoe vortex were determined by using forward difference technique of computational hydrodynamics and Stokes theorem, respectively. The horseshoe vortex flow and turbulence characteristics were discussed from the standpoint of similarity with velocity and turbulence intensity characteristic scales.