Second Moment Closure Modeling of Stratified Wake Flows
Abstract
Executive SummaryA 20-month program is offered to pursue research activities related to Second-Moment Closure Modeling (SCM) of stratified wake flows. The proposed work is a continuation of a current ONR 331 project, N00014-19-1-2057, which expires in June 2023. This research will result in a new SMC model set that will return at least the same accuracy as current conventional Full Reynolds Stress Models for unstratified wakes (i.e., progressive modeling) but which will significantly outperform all currently available RANS models for stratified shear/wake flows.Statement of WorkTask 1. Algebraic Dissipation Tensor Model Development. We will finalize an algebraic model for dissipation anisotropy in stratified wakes, initiated in recent months. Results to date are significantly improved compared to the baseline isotropic dissipation model.Task 2. Pressure Diffusion Model Development. We will develop a DNS and data-based differential model for pressure diffusion. Our recent work using DNS of stratified wakes illustrated the significant budgetcontribution of pressure diffusion, which is neglected in virtually all FRSMs. That work unambiguously motivates efforts to developmodels for it explicitly.Task 3. Dynamic Model for Coherent Structures. We will develop a coherent-structure based multi-scale model for accommodating the large spanwise rollers (pancake eddies) that arise in the NEQ and Q2D regimes of stratified wakes. Our recent work illustrated significant differences between baseline FRSM and DNS wake heights. Our recent DNS simulations of a low Froude number wake in the NEQ regime, capture these coherent structures, as have the DNS and LES computations of other workers. These scales are inaccessible to the 2D+t SMC analysis widely used in the Navy, so we propose a two-time-scale averaging approach, wherein the important dynamics of these rollers are modelled using ensemble-averaging of the DNS data, in a manner uncoupled from the smaller scales implicit in Reynolds averaging.DeliverablesThe deliverables of this program will be contributions to a PhD thesis, journal publications, ONR reporting/documentation and technical review attendance/presentation.Year 1 (GFY 2023-2024): ONR reporting/documentationand technical review attendance/presentation.Year 2 (GFY 2024-2025): ONR reporting/documentation and technical review attendance/presentation, demonstrated progress on PhD thesis, conference and journal publications.Approved for Public Release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 24, 2023
- Source ID
- N000142312695
Entities
People
- Robert Francis Kunz
Organizations
- Office of Naval Research
- Pennsylvania State University
- United States Navy