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Fix handedness for bingham average #7297

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Fix handedness for bingham average #7297

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a3f0d6d
check for handedness in bingham average
Theo-Geo Aug 18, 2026
55031ab
remove assert to enable 2D cpo calculations
Theo-Geo Aug 18, 2026
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23 changes: 20 additions & 3 deletions source/particle/property/cpo_bingham_average.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -270,6 +270,13 @@ namespace aspect
const Tensor<1,3,double> eigvec_b = eigenvectors_b[0].second;
const Tensor<1,3,double> eigvec_c = eigenvectors_c[0].second;

// compute cross product to check for handedness of output rotation
double handedness = 0;
for (unsigned int i1=0; i1<3; i1++)
for (unsigned int i2=0; i2<3; i2++)
for (unsigned int i3=0; i3<3; i3++)
handedness += Utilities::Tensors::levi_civita<3>()[i1][i2][i3]*eigvec_a[i1]*eigvec_b[i2]*eigvec_c[i3];

// build rotation matrix from the eigen vectors
Tensor<2,3> R_CPO;
R_CPO[0][0] = eigvec_a[0];
Expand All @@ -278,9 +285,19 @@ namespace aspect
R_CPO[0][1] = eigvec_b[0];
R_CPO[1][1] = eigvec_b[1];
R_CPO[2][1] = eigvec_b[2];
R_CPO[0][2] = eigvec_c[0];
R_CPO[1][2] = eigvec_c[1];
R_CPO[2][2] = eigvec_c[2];
// ensure right-handedness
if (handedness < 0)
{
R_CPO[0][2] = -eigvec_c[0];
R_CPO[1][2] = -eigvec_c[1];
R_CPO[2][2] = -eigvec_c[2];
}
else
{
R_CPO[0][2] = eigvec_c[0];
R_CPO[1][2] = eigvec_c[1];
R_CPO[2][2] = eigvec_c[2];
}

// convert rotation matrix to euler angles phi1, theta, phi2
Tensor<2,3> Rot = transpose(R_CPO);
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4 changes: 0 additions & 4 deletions source/particle/property/crystal_preferred_orientation.cc
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Expand Up @@ -1236,10 +1236,6 @@ namespace aspect
void
CrystalPreferredOrientation<dim>::parse_parameters (ParameterHandler &prm)
{
AssertThrow(dim == 3, ExcMessage("CPO computations are currently only supported for 3d models. "
"2d computations will work when this assert is removed, but you will need to make sure that the "
"correct 3d strain-rate and velocity gradient tensors are provided to the algorithm."));

prm.enter_subsection("Crystal Preferred Orientation");
{
random_number_seed = prm.get_integer ("Random number seed");
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