Best Practice Advice AC1-09: Difference between revisions
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==Computational Domain and Boundary Conditions== | ==Computational Domain and Boundary Conditions== | ||
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Place the far field at a minimum of 3 root chords from the wing. | |||
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==Discretisation and Grid Resolution== | ==Discretisation and Grid Resolution== | ||
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Revision as of 15:29, 12 March 2015
Vortex breakdown above a delta wing with sharp leading edge
Application Challenge AC1-09 © copyright ERCOFTAC 2024
Best Practice Advice
Key Fluid Physics
The flow around a delta wing with a sharp leading edge at high angle of attack is characterized by the main vortex developing above the wing. The vortex is formed as the shear layer emanating from the leading edge rolls up, starting immediately at the apex. At high Reynolds numbers, the shear layer rapidly becomes unstable and a turbulent vortex is formed. At a sufficiently high angle of attack, the vortex breaks down: the high axial velocity in the vortex core drops rapidly to a value close to zero.
To properly capture this flow, it is essential to capture the shear layer separating from the leading edge. In particular, the instability of this shear layer must be captured. It is recommended to verify these key properties using visualization of the instantaneous flow field (e.g., using the Q criterion).
Application Uncertainties
\begin{itemize} \item Use a time sample of at least 7 convective time units to compute statistical data in order to obtain statistical convergence. (Make sure the transient is not included in the time sample.) \end{itemize}
Computational Domain and Boundary Conditions
\begin{itemize} \item Place the far field at a minimum of 3 root chords from the wing. \end{itemize}
Discretisation and Grid Resolution
Physical Modelling
Recommendations for Future Work
Contributed by: J.C. Kok, H. van der Ven, E. Tangermann, S. Sanchi, A. Probst, L. Temmerman — '
© copyright ERCOFTAC 2024