Turbulence Measurements in Simulated Tidal Flow

Field measurements of tidal flow have shown that there is an increase in turbulent parameters (turbulent intensity, Reynolds stress, coefficient of turbulent diffusivity, and the rate of sediment transport) when the flow is decelerating as compared with when it is accelerating. A series of experiments were conducted to study the effect of unsteady flow on turbulence characteristics. The flow in a long flume was accelerated and then decelerated for the same periods of time. Instantaneous velocity components in three directions, water surface slope, and shear stress at bed were measured. From measured data mean velocity profiles, temporal and spatial Reynolds stress profiles, and energy spectra were determined. The results were compared, wherever possible, with those obtained from field measurements.