1. Evaluation of curvature correction methods for tip vortex prediction in SST [formula omitted] turbulence model framework.
- Author
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Asnaghi, Abolfazl, Svennberg, Urban, and Bensow, Rickard E.
- Subjects
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MATHEMATICAL models of turbulence , *FLUX flow , *RANKINE cycle , *COMPUTER simulation , *KINETIC energy , *ENERGY dissipation - Abstract
Highlights • Different curvature correction models are described, and incorporated into the SST k − ω model • By considering the classical Rankine vortex, the response of the curvature correction models in the viscous vortex core, and in the inviscid outside region are investigated. • It is shown that some of the curvature correction models are so sensitive to their clipping values, or their calibration parameters. • It is noted that the curvature correction models that can accurately predict the tip vortex flow fields, alter the boundary layer behaviour on the foil, and form a leading edge vortex. Abstract This paper presents and studies effects of curvature correction (CC) methods to improve two equation RANS simulations of tip vortex flows, exemplified using the SST k − ω turbulence model. Performance of the CC models is first evaluated in the classical Rankine vortex flow field, and then extended into the study of tip vortex flows over an elliptical foil. The results have been compared with experimental measurements in terms of the vortex strength and velocity field, and the importance of the turbulence closure in tip vortex simulations is highlighted. Contribution of the CC models in different terms of the turbulent kinetic energy and specific dissipation transport equations are described, and it is discussed why a CC model may have mesh resolution dependent results. By considering the distribution of the CC function, it is shown that although some of the models can predict the location of the tip vortex core accurately, they still do not significantly improve the vortex prediction as the impact on the turbulent viscosity is wrong or not enough. It is further noted that as some of these models have been calibrated on specific vortex flows, they may not be completely applicable for other cases without recalibration. It is shown that some CC models provide accurate tip vortex predictions, primarily the ones based on the sensitization of the turbulent viscosity. Further, it is noteworthy that the successful models are active not only around the vortex, but also change the boundary layer characteristics on the foil, and the boundary layer separation lines, which consequently can provide the required momentum for the vortex core accelerated axial velocity. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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