TURBULENCE MEASUREMENTS IN THE BOUNDARY-LAYER OVER A SAND WAVE FIELD

To assist in elucidating the turbulent structure of flow over regular sets of bed forms, data procured with small mechanical current meters above 2m high 96m long sand waves in the Columbia River are analyzed. The high-frequency resolution of the flow sensors and the half hour records that were collected with them are shown to be sufficient to yield reliable Reynolds stresses. In addition, an expression from which the sampling error in Reynolds shear stresses can be estimated from the sampling frequency, the local flow speed, and the distance from the boundary is presented.-from Authors