Flow field around side-by-side piers with and without a scour hole

► We make a comparison of flow field between single and side-by-side piers by an ADV. ► Between the two piers, downflow and horseshoe vortices are strong. ► The values of turbulence kinetic energies and intensities increase between the two piers. ► Between the two piers, contracted flow and strong horseshoe vortices cause higher scour depth.