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I'm trying to solve aerodynamics of whole aircraft by vortex lattice method (or deeper here). The problem is that sometimes trailing vortex filaments from Horse Shoe Vortexes of main wing hits panels of rudder/elevator which leads to singularities (infinite coupling between the two panels).

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Is there good way to damp those singularities? I was thinking something like adding imaginary part to expression for vortex filaments might help, but than vorticity is not exactly conserved.

This is related to my previous question which was prehaps a bit long, unclear and unfocused.

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In my experience programming potential flow methods, the best way to avoid those singularities is to do both of these two actions:

  1. Program your code to neglect the influence of that specific vortex line segment over the collocation point if the distance between that point and the line, orthogonally to the line, is of less than a threshold (which should be close to machine zero);
  2. Ensure your main wing vortices are lined up with the empennage vortices. This is essential to make sure your AICs relating the strength of the main wing vortices and the influence velocities at the empennage correspond to a realistic velocity distribution.

Your situation, however, is most definitely inaccurate, even taking these measures.

Vortex lattice assumes a straight wake, which is not true considering how the velocity field is affected by a horizontal tail near the wing wake. You can read more about it in the section on wake rollup, in Katz & Plotkin's Low-Speed Aerodynamics, chapter 14.

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