Modeling and Simulation of Unequal Trailing Vortex Pairs
Abstract
The trailing vortex structures generated by control or lifting surfaces are often created in pairs ormay encounter other vortices engendered by their flow configuration. The coupled interactions ofthese line vortices can lead to vortex merger or cooperative instability that will define the state ofthe downstream flow and may impose significant unsteady fluid loads on nearby solid structures.Induced stretching of the weaker vortex in unequal vortex pairs drops its core pressure sharplyand can cause cavitation inception, which can further complicate the overall vortex dynamics. Anengineering model to estimate this inception location for vortex pairs is presently lacking, as is acomplete understanding of the coupling of the large-scale dynamics of vortex pairs with the flowfield within their cores during the stretching process. These knowledge gaps motivate the presenttheoretical and computational investigation into the long-time, nonlinear evolution of generalizedline-vortex pairs, where the more realistic scenario of vortices emanating fromeither a fixed ormoving location in space is favored over the classical approach assuming infinite vortices. Thisinvestigation willconduct large-eddy simulations of isolated and paired vortex configurations inconjunction with theoretical predictions for the nonlinear evolution of unequal vortex pairs usingthe Klein-Majda vortex framework; these efforts will be validated against available experimentaldata that will connect the fluid mechanics of interest to the conditions for cavitation inception.The overarching basic research objective is a detailed understanding of how the asymmetries ofco-rotating and counter-rotating vortex pairs (e.g., unequal vortex strengths, different core sizes,or vortex misalignment) affect the dynamical evolution of the pair until nonlinear saturation ordestabilization occurs. A successful research program will initiate a parametric map of the likelymode of instability or breakdown for the vortex pair based on its initial state; inform a predictivemodel for the location of inception for realistic hydrodynamic configurations that is grounded inbasic fluid mechanical principles; and connect the occurrence of extreme stretching events ofsecondary vortices to nonlinear vortex induction mechanisms, where appropriate. The anticipatedpractical advantage of these outcomes is theability to use data that may be produced by low-cost(Reynolds-averaged) computational simulations of hydrodynamic flows as an initial condition orparameter set to inform reliable vortex stability or cavitation susceptibility predictions that wouldotherwise require immense computational resources.APPROVED FOR PUBLIC RELEASE
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 08, 2024
- Source ID
- N000142412111
Entities
People
- Justin W Jaworski
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech