Use Gram-Schmidt for create_mrt_orthogonal

• orthogonalize automatically if no moments from literature are provided
• must specify whether weighted or unweighted orthogonality is desired
• add lbmpy.moments.is_bulk_mode and make lbmpy.moments.is_shear_mode also detect the diagonal modes
• use the bulk mode (
  $x^2+y^2+z^2-1$
  ) in orthogonalization so we get the same physical modes as in literature

We now match the literature MRTs in all the physical moments. The only exception is D3Q27, which chooses a different linear combination for the shear moments. Differences in the higher-order moments remain, but they have no effect on the model.

Fixes #5 (closed)

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• 2d71930a - Use Gram-Schmidt for create_mrt_orthogonal

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• 38ccdf6c - lbmpy.moments.is_{bulk,shear}_moment

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• a2f07b9b - lbmpy.moments.is_{bulk,shear}_moment

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• 1ebe2216 - create_mrt_orthogonal: use the same viscous moments as in literature

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• 9f29efa8 - Add D2Q9 MRT from literature

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unmarked as a Work In Progress

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• 2856e2d5 - fix broken tests

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• 23402c65 - fix broken tests

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There is one failing test, lbmpy_tests/test_relaxation_rate.py::test_relaxation_rate. I don't fully understand what it does, but it seems like it doesn't like my overhaul of is_shear_moment. Other than that, this pull request is complete.

This test was wrong - should be fixed now

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• 77ba9818 - Orthogonal MRT

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• ffa330f9 - Orthogonal MRT

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merged

mentioned in commit 15992f4a