Lift predictions
Updated April 30, 2023------------------ WORK IN PROGRESS ------------------
Context
Lift predictions in the case of thick surface methods are regularly higher than in the case of thin surface methods. The differences are not significant in the case of flat wakes, and are within the precision which can be expected of panel methods.
As reported by a couple of flow5 users, the difference becomes more noticeable when a Vortex Particle Wake (VPW) is used.
The purpose of this page is to report this difference in predictions for which no obvious explanation could be found.
Description
The project file used for the following calculations can be found here.
The difference in predictions goes back to xflr5. This can be illustrated with the calculation of a simple rectangular wing with both a VLM and the thick surface / quad panel method. The lift coefficient is higher in the latter case.
Similar observations can be made with flow5's triangle methods.
This difference is more pronounced in the case of a VPW.
Jibe 2 case
The same observations can be made in the case of the Jibe 2 experiment. The difference in predictions however is within the margin of error of panel methods and is not significant.
Conclusion
This higher lift predictions of thick surface methods compared to thin surface methods is a repeatable trend for which no obvious explanation could be found.
It is more pronounced when the wake is modeled as a VPW.
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