LDA measurements of steady streaming flows of Newtonian and viscoelastic fluids

LDA experiments have been conducted in a two-dimensional steady streaming flow field in order to determine the secondary velocity profiles. We describe here an LDA system developed to resolve small secondary-flow velocities and to detect flow reversals due to viscoelasticity. Results compare well with theoretical predictions. A detailed analysis of the errors and uncertainties involved in the measurements confirms the reliability and reproducibility of the measurements. Although the method has been applied here to a specific flow field, the technique should be applicable to a number of secondary flows, such as those which can occur in curved pipes and in oscillating pipe flows.