Date of Award
Master of Science (MS)
John P. Crimaldi
A scalar plume is the spatial and temporal structure of a released scalar, such as heat, chemical or contaminant. The resulting downstream structure is governed by the 3D Advection-Diffusion equation, which couples both advection, through the Navier Stokes equations, and diffusion describing the relative relationship and structure of the plume. Solutions to these equations for turbulent flows are computationally expensive and therefore most of the understanding surrounding turbulent plume structure stems from experimental results. Currently, a majority of experiments investigating plume structure have been done in aqueous environments using planar laser-induced fluorescence (PLIF), while in gaseous environments experiments utilize single point ion detection techniques. This thesis adapted a current gaseous PLIF technique to study airborne 2D scalar plume structure to be suitable for capturing neutrally buoyant plume-like data under two boundary conditions: (1) free-stream release, and (2) near bed release. Processing of the two collected datasets included investigations into instantaneous behavior and computation of relevant statistical metrics including mean concentration, RMS of concentration fluctuations, and intermittency. Results in the free-stream and near bed data differ greatly in the instantaneous and statistical comparisons, suggesting a significant difference in airborne plume behavior once a boundary is introduced.
McHugh, Margaret, "Laboratory Investigations of Gaseous Plume Structure Using Planar Laser-Induced Fluorescence" (2017). Civil Engineering Graduate Theses & Dissertations. 74.