An improved passive vortex generator model for flow separation control

Authors: von Stillfried, , Wallin, S.W., Johansson, A.V.J.
Document Type: Conference
Pubstate: Published
Journal: 5th AIAA Flow Control Conference, Chicago, IL, USA
Volume: AIAA-2010-5091  
Year: 2010


Modeling arrays of passive vortex generators (VGs) pairs located in the fully turbulent boundary layer of a two-dimensional flat plate, generating streamwise counter-rotating vortex structures is investigated. Usually, a sound computational fluid dynamics investigation requires an adequate grid with a corresponding large number of grid points around such VGs in order to obtain an accurate solution. This leads to a time-demanding grid generation which often comes along with lots of challenges during the creation. An effective way to get around this time-consuming process is to introduce a way to model these flow separation devices statistically and, by that, to add their statistical physical effects to the governing equations rather than resolving their geometries in the computational grid. Here, a computational tool for statistical VG modeling is presented that makes it possible to simulate and model passive VGs in wall-bounded flows, whereas the need for a local mesh refinement is no longer required. Previous research results of the presented statistical modeling of passive VGs have shown that it is necessary to improve the original statistical VG model in terms of the vortex stress modeling in order to evaluate results not only qualitatively, but also quantitatively. Computational results for spanwise averaged fully resolved three-dimensional VGs, experimental results, as well as two-dimensional original VG model results are evaluated and compared to two improved statistical VG model approaches that are presented here. It is shown that the improved VG models gives better results than the original VG model in terms of the nearfield vortex stresses that are important for the immediate response of the boundary layer flow on momentum mixing. The impact of the improved VG models on flow separation control could be proven to be stronger and thus, closer to experiments and fully resolved results.