Towards realistic prediction and modeling of the hydrodynamic disturbances of complex bodies and initial conditions in a stratified ambient: laboratory experiments
Abstract
Abstract for Towards realistic prediction and modeling of the hydrodynamic disturbancesof complex bodies and initial conditions in a stratified ambient: laboratory experimentsMuch information has been gathered through numerical simulation and through laboratoryexperiment on wakes of generic bodies, such as a sphere, in a stratified environment.Recent efforts have become quite sophisticated in spatial and temporal resolution at earlytimes. A number of questions remain, all of which have to do with making these studiesrelevant to real-world operations.Objectives and open questions(i) Are there practically-motivated variations in initial conditions that will change ourphysical modeling of the intermediate wakes where stratification begins to exert asignificant influence? (ii) What kinds of quantities vary with changing upstream inputs?(Do they matter?) (iii) Is there a robust way to determine when wake conditions havecertain pattern information in them? (iv) How do the experiments scale over {Re, Fr}, andhow might they scale to much larger values? (v) Is there a way in which laboratoryexperiments and simulations can be used to make predictions over realistic ranges ofparameter space? This parameter space may need to include further geometric parametersfor bodies and conditions of practical interest.Technical approachTwo sets of experiments will be conducted in our 2.5 length tow tank, one with a prolatespheroid at angle of attack (various angles), and one set with a delta wing with the purposeof making a trailing vortex pair directly. The flows will be interrogated with a tomographicPIV system, which itself be qualified and tested so that likely uncertainties in velocitygradient quantities are known.Expected results(i) New experimental data will be available for stratified wakes of two types, where initialconditions are deliberately seeded with asymmetry, or vortex topology. (ii) The wakedescriptions will run from early (turbulent) to intermediate (wave-generating) times whenthe persistent late-wake patterns are developed. (iii) The data will be of time-resolvedthree-dimensional velocity fields and their spatial gradients. (iv) Estimates of patterndetection and recognition will be made, using empirically-tuned in-house DMD methods,and in collaboration with alternative, data-driven algorithms. (v) Detailed comparisons willbe made with three groups running numerical simulations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 17, 2020
- Source ID
- N000142012584
Entities
People
- Geoffrey Spedding
Organizations
- Office of Naval Research
- United States Navy
- University of Southern California