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SIMION 8.0 Issues/Bugs/Enhancements

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Issue I372 [enhancement,high]
  Define open boundaries explicitly with Neumann conditions?
  See ryan20100628
    The following change to the "symmetry refining equations"
    shown near the beginning of the "Computational Methods"
    chapter of SIMION 7.0 and 8.0 manuals is suggested (davidm-200703).

    Non-mirrored 2D planar PA boundaries shall be changed from

      All edge points: P0 = (P1+P2+P3)/3 {top edge}   to
      All edge points: P0 = (P1+P2+P3+P4)/4 = (P1+P2+2*P3)/4 {top edge}
      (note: assuming P4 = P3)

    The latter is the same Neumann boundary condition imposed when
    mirroring is enabled.

    Non-mirrored 3D and 2D cylindrical PA boundaries shall be changed

    This change seems to make little numerical difference in practice
    (though perhaps further testing is needed), and it seems to put
    the non-mirrored open boundaries on firmer theoretical footing.
    At least, I'm not sure the current form has much theoretical
    justification, though it does work very much like a Neumann
    boundary in practice.

    The change will also more formalize the understanding that it is
    possible to define mirror planes on both left and right (X-plane)
    sides of a PA since the edges are in fact Neumann boundaries,
    which mirror planes behave identically to.

    The change is fairly trivial to make.

  Resolved in 8.1.0-TEST4 (for details, see the section titled
  "Neumann boundary conditions" in the SIMION 8.1 help file.

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