Visualization studies of cloud-like flows

Abstract

This paper reports a series of flow visualization studies in which cloud-like off-source volumetric heating is injected into fully developed turbulent flow, with the objective of simulating the effect of the heat release that accompanies condensation and freezing of water vapour in a cloud. The visualizations provide axial and normal sections of the flow using laser sheet illumination. Special emphasis is placed on a comparison of the results obtained in jets and plumes. Although the results are broadly similar in both flows, the plume (which should be closer to a cloud) shows greater dilution due to entrainment before heating, and stronger effects due to heating. In particular, heating is shown to arrest the spread of the plume and cause considerable disruption of the large eddies in the flow. It is concluded tbat heat release due to phase change in a cloud bas not only thermodynamic but subtle and important fluid-dynamical consequences as well.