Horizontal round heated jets into calm uniform ambient

Abstract

In this article, we investigate horizontal, round, turbulent buoyant jets that discharge in a homogeneous calm ambient fluid. In a series of experiments performed, the initial jet Richardson numbers ranged from very small (jet-like) to around unity (plume-like), to include the full extent of applications. The mixing characteristics such as trajectories obtained with video imaging, turbulence properties measured with fast response thermistors, and dilution factors are evaluated. The trajectories of buoyancy-conserving horizontal jets bend faster than those observed in heated jets. The flow resembles a jet-like behavior in the 'horizontal' regime, while the mean and turbulent temperature profiles become asymmetrical in the transition and the 'vertical' regime. The maximum intensity of turbulence doubles in the 'vertical' regime if compared to that in the 'horizontal' part of the flow. Minimum dilutions obtained from experiments at the jet axis are compared to the results of a one-dimensional numerical model of a heated horizontal jet, where the loss of buoyancy flux has been accounted for.