Experimental analysis of slow viscous flow using photoviscosity and bubbles

TLDR: In this article, the principal strain rates and the maximum shear stress from photoviscotity were determined for slow viscous flow about a cylindrical obstacle in a rectangular channel.

Abstract: Photoelasticity in solids is a well-developed technique for stress and strain analysis. Less progress has been made in applying a similar effect, photoviscosity, to flow analysis. This paper has three objects: (1) to simplify photoviscous methods; (2) to compare velocity profiles obtained from photoviscosity with those obtained by the double-exposure bubble technique; (3) to determine the principal strain rates and the maximum shear stress from photoviscotity. The problem of slow viscous flow about a cylindrical obstacle in a rectangular channel was selected for the comparison. The fluid was a suspension of milling yellow dye in water. Strain rates and stresses averaged over the path of ligh can be obtained easily using photoviscosity. The bubble technique is shown to be a very powerful tool that permits the determination of the velocity field in three-dimensional problems.