Enforcing volumetric velocity condition throughout the domain for the entire simulation isn't physically accurate about fluidx3d

[ProjectPhysX]

This is only an initial condition. The velocity y-component is free to change in the entire box, except in the TYPE_E cells at the box boundary, where the initial velocity (0, u, 0) is enforced for all time steps.

If you enforce u only at the inlet side, it is not set at the other TYPE_E walls, and they enforce 0 velocity (but are non-reflecting, so allow tangential flow/outflow). This isn't wrong, but I haven't tested that myself yet.

Note that the initial state of the velocity field remains in lbm.u GPU memory unless lbm.update_fields() is called. Until then, the new velocity field state is only stored in the LBM density distribution functions. To update the velocity field in CPU memory, you also have to call lbm.u.read_from_device().