Scalar Dispersion in Homogeneous and Stratified Turbulent Flows
Abstract
The proposed effort focuses on experimental and theoretical investigations of high Schmidt number dispersion and plume formation ofa passive scalar injected from a point source in turbulent flows in a laboratory environment in water. Scalar dispersion phenomena we propose to investigate include the development of plumes in grid-generated turbulence, in both homogeneous- and stratified-density flows, the formation of mean and fluctuating scalar profiles, spatial scalar spectra, and other scalar-field statistics. In the first part of the proposed effort, we propose to process and analyze a volume of data acquired in previous grid-turbulence experiments, conducted in homogeneous-density flows. These utilized experimental and diagnostic techniques that were applied to flows generatedin a computer-controlled tow-tank facility developed for the purpose. We propose to cover grid-mesh Reynolds numbers in the range, 2x10^3 <= Re_M <= 5x10^4, spanning from below to above mixing-transition Reynolds and Taylor-Reynolds numbers, as documented in grid turbulence and many other turbulent flows. We will investigate the influence of parameters relevant to high Schmidt number scalar dispersion and downstream plume formation and development, over mesh lengths downstream of the grid in the range, 10 <= x/M <= 110, assessing results and theory, and comparing with those of previous experimental and theoretical work.In a second part of the proposed effort, we propose to extend these investigations to stratified-density turbulent flows. For this part of the effort, we proposeto augment and modify the existing tow-tank facility, as necessary, as well as develop equipment and instrumentation in support of the new experiments, combining optical shadowgraphy and laser-induced fluorescence (LIF) techniques, to the extent feasible, with conductivity, temperature, and other local measurements. As part of the optical measurements, we propose to investigate exploiting variable index-of-refraction (IOR) fields encountered in stratified flow in the laboratory environment, as well as explore methods to mitigate them, depending on how the stratified-flow environment is produced. Approved for public release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412600
Entities
People
- Paul Dimotakis
Organizations
- California Institute of Technology
- Office of Naval Research
- United States Navy