transfer_field

Moves a result from one solver's output into another solver's input.

Group: Two solvers on one problem.

Parameters

Parameter	Type	Required	Default
source_vtu	string	yes
field_name	string	yes
interface_coord	number	yes
interface_axis	integer	no	0
target_format	string	no	'json'
output_path	string	no	''

What the model reads

The text below is the tool's own description, exactly as the AI model receives it.

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Extract field values at an interface from a VTU file and format for transfer.

Universal data connector for cross-solver coupling. Reads VTU output
from any solver, extracts values at the interface plane, and formats
them for the target solver's expected input shape.

FIELD (VOLUME) COUPLINGS: pass `interface_axis=-1`. Not every coupling
exchanges data on a surface. In thermo-structural interaction both
participants own the WHOLE body and exchange volume fields — the
temperature one way and the volumetric strain the other — so there is no
interface plane, no normal and no flux to balance, and a plane slice
cannot express the exchange at all. With `interface_axis=-1` every point
in the file is taken, `interface_coord` is ignored, and the points come
back in a fixed lexicographic order (the `couple` driver relaxes export
vectors entry by entry, so the order must not move between iterations).

Args:
    source_vtu: Path to VTU result file from the source solver.
    field_name: Field to extract (e.g. 'temperature', 'displacement').
    interface_coord: Coordinate value defining the interface plane.
        Ignored when interface_axis is -1.
    interface_axis: Axis perpendicular to interface (0=x, 1=y, 2=z), or
        -1 for the WHOLE VOLUME (field coupling, see above).
    target_format: Output format. Options:
        - "json"        — interface coordinates + values (default)
        - "fenics"      — Python BoundaryCondition snippet (Dirichlet
                          at this interface), saved as .py
        - "4c_neumann"  — 4C-format YAML snippet for a Neumann
                          boundary condition, saved as .yaml
    output_path: Where to save the formatted output. If empty,
        auto-generated next to the source VTU as
        'interface_<field_name>.<ext>'.

Returns:
    A summary string with the interface min/max/mean and the path
    of the saved file.