I just noticed that the BC implementation types look wrong in peclet/tests/MMS_2D_VariableVelocity.prm.
Referring back to my master's thesis, the strong/Dirichlet boundary is the bottom (minimum y) boundary, while the rest are natural/Neumann. So we should have "implementation_types = natural, natural, strong, natural".
I just noticed that the BC implementation types look wrong in peclet/tests/MMS_2D_VariableVelocity.prm.
Referring back to my master's thesis, the strong/Dirichlet boundary is the bottom (minimum y) boundary, while the rest are natural/Neumann. So we should have "implementation_types = natural, natural, strong, natural".