Function lower_ale_fsi_cartesian_2d 

pub fn lower_ale_fsi_cartesian_2d(
    program: &KernelProgram,
) -> Result<AleFsiCartesianModel<2>, Diagnostic>

Lower one complete 2D conservative transient-flow FSI network.

The function reuses the same transient Navier–Stokes and dynamic-solid recognizers used by their standalone projections. It adds no ALE semantic node and accepts no mesh or numerical policy.

Errors

Returns EQ0703 when the typed subdomain assignment, live interface, or whole-model closure is not unique and exact.