Dynamic pressure fields in a local scour hole formed by a submerged wall jet

Abstract

Previous studies investigated the flow in a local scour hole mainly from two perspectives, i.e. mean velocity and turbulence, but there is no literature exploring it from the perspective of pressure. This study investigates the dynamic pressure fields in a local scour hole formed by a wall jet using PIV (particle image velocimetry) data to solve the Navier–Stokes (N-S) and Reynolds-averaged Navier–Stokes (RANS) equations, respectively. A comparison between the two cases with the effect of turbulence (solved by RANS equations) and without the effect (by N-S equations) reveals that turbulence reinforces pressure in the local sour hole. The wall jet experiences cyclical energy transitions in the forms between kinetic energy and pressure energy over its interactions with the sediment bed and the water surface. It is revealed that pressure energy is predominant by examining the ratios of the pressure energy to the average kinetic energy in the scour hole.