Incompressible Navier-Stokes with particular scheme & mixed elements FEniCSx

[dokken]

@TOP1

2023-01-25 08:59:10.937 (   0.165s) [main            ]       NewtonSolver.cpp:36    INFO| Newton iteration 0: r (abs) = 0 (tol = 1e-10) r (rel) = -nan(tol = 1e-06)
2023-01-25 08:59:10.937 (   0.165s) [main            ]       NewtonSolver.cpp:255   INFO| Newton solver finished in 0 iterations and 0 linear solver iterations.
Number of interations: 0
2023-01-25 08:59:10.992 (   0.220s) [main            ]             loguru.cpp:526   INFO| atexit

This means that your initial velocity guess 0, solves the problem, which likely indicates that you have an issue with your boundary conditions.
I would strongly recommend making sure that the correct parts of the domain is marked, and that the boundary condition is correct by first:

1. Write the facet markers to file, and check that they are sensible
2. Use dolfinx.fem.petsc.set_bc on a Function and write it to file, to check that the correct boundary condition is applied. (see for instance: Setting initial condition on irregular boundary from marked input mesh - #2 by dokken)