Visualization of the viscous flow induced by a round jet

Abstract

The flow induced by a laminar round glycerol jet emerging from a plane wall is investigated. The flow field (jet region as well as outer flow field) is visualized by means of very small bubbles suspended in the fluid. For slender jets the observed flow pattern disagrees with both potential-flow theory and Squire's ‘exact’ solution, but it is in excellent agreement with results of an asymptotic analysis by Schneider (1981). At a downstream distance that depends exponentially on the square of the Reynolds number, the jet develops into a toroidal eddy as predicted by Schneider (1985). In an apparatus of reasonable size the eddy can be observed only in a very limited Reynolds-number regime.