Experimental Study of Bedforms Generated by Pseudoplastic Fluids in Flumes

The results of an experimental study on the bedforms generated in a non-cohesive granular bed in a flume due to the laminar flow of a pseudoplastic fluid are presented in this paper. The morphological characteristics of the bedforms are determined with a non-intrusive method, by means of two illuminating planes generated by lasers, that define a couple of illuminated lines on the bed which are distorted when the bed is deformed. After recording and processing the distorted lines, the amplitude, wavelength and celerity of bedforms can be calculated, as well as the bedload. The dimensionless bedload depends on the effective viscosity and on the excess of the shear stress deficit. The bedform amplitude is independent of both Reynolds and Froude numbers. The wavelength does not show a dependency on the Reynolds number, presenting a slight increasing tendency with the Froude number.