Turbulence Characteristics of Sediment‐Laden Flows in Open Channels

The turbulence characteristics of sediment‐laden flows in open channels are investigated using two‐component laser‐Doppler velocimetry. Suspensions of well‐sorted sands with diameters ranging from 0.15 mm to 0.24 mm, flowing over nominally flat beds, both fixed and erodible, are studied in a tiltable, recirculating flume. Various conceptual models that have been proposed to explain the mean‐field profiles are examined for consistency with respect to their implications for higher‐order characteristics. No evidence is found to support either the traditional model, associated with a decrease in the von Kármán constant, or the more recently proposed models based on simple analogies to slightly stably stratified wall‐bounded flows. A model based on small‐scale fluid‐particle interaction is suggested as more promising.