Experimental characterization of Newtonian and non-Newtonian fluid flows in corrugated channels

The main goal of this experimental study is to determine the friction mechanisms which govern transfer properties on corrugated walls with large amplitude. We have considered Newtonian and non-Newtonian pseudoplastic fluids for the laminar or turbulent flow regimes. Experiments rely on the use of two different techniques: the electrochemical method used for the measurement of the wall shear rate S and the laser velocimetry for the determination of the axial velocity profiles. Our local observations for a wavy two-dimensional channel especially concern the evolution of mean and fluctuating variables as a function of the flow rate or of a generalized Reynolds number. Some new results are presented for the different flow regimes and their specificities. The influence of the pseudoplasticity character on the wall transfer, on the shape and position of recirculating zones downward the undulations has been pointed out. (C) 1999 Elsevier Science Ltd. All rights reserved.