Developments in hybrid approaches : Vortex method with known separation location ; Vortex method with near-wall Eulerian solver ; RANS-LES coupling
(2006)
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- Authors
- Supervisors
- Winckelmans, GrƩgoire
- Abstract
- (en) Predicting and understanding turbulent flows is still a partially open problem. This thesis is specifically focused on incompressible external aerodynamics. Lagrangian vortex element methods are well suited to simulate these type of flows but were limited to moderate Reynolds numbers. Here, hybrid approaches are proposed to overcome this limitation. First, flows that can be modeled using prescribed separation regions are investigated using simplified approaches. While they allow to handle high Reynolds number wake flows, only limited quantitative results can be obtained. Therefore, a new approach that combines an Eulerian grid-based solver and a Lagrangian solver is developed. This hybrid approach suppresses the biggest limitation of vortex methods: it allows to efficiently handle the boundary layer regions using the Eulerian solver. Another contribution is the development of a conservative redistribution scheme for hierarchically refined grids. It provides the required control on the spatial accuracy. The capabilities of the new scheme are demonstrated on the flow past a hemisphere at Re=3,000. Then, an application of vortex methods to a complex, turbulent, real-life problem is shown through the investigation of aircraft wake vortices in ground effect. The results light the path for future work: the developments made for the pure Lagrangian method should be transfered to the Vortex-In-Cell approach, as it is an order of magnitude faster. Finally, a hybrid RANS-LES turbulence modeling formulation is investigated and further adapted. While results are encouraging, the extension of the method to complex geometries is not trivial. Nevertheless, the core idea of the approach should be kept in mind as it could be adapted to more general RANS-LES approaches.
- Affiliations
Citations
Daeninck, G. (2006). Developments in hybrid approaches : Vortex method with known separation location ; Vortex method with near-wall Eulerian solver ; RANS-LES coupling. https://hdl.handle.net/2078.5/131411