Turbulence Characteristics of Flow over a Block Ramp

Block ramps are structures consisting of boulders on steep slope and used for the stabilization of streams by dissipation of energy of flow by means of generating excessive turbulence. This paper deals with experimental study of turbulence over a block ramp. Three-dimensional velocities were measured by acoustic Doppler velocity meter at a constant depth along the block ramp in the developing flow zone. Spiky velocity data were removed using computer code developed in this study for four filtering methods. Out of other filtering methods, the velocity correlation method was found more effective. Spatial variation of turbulence intensities, Reynolds stress, turbulent kinetic energy and skewness coefficients of velocity fluctuations along the length of block ramp were studied. The longitudinal turbulence intensity increases along the ramp length, while the vertical turbulence intensity decreases. Reynolds stresses and turbulent kinetic energy increase along the block rampas a result of development of boundary layer. Skewness coefficients of the longitudinal and transverse velocity components were observed to be uncorrelated with the block ramp length whereas skewness coefficient of vertical velocity component was observed to vary linearly with the length of block ramp.