[FXC-6102] fix(): avoid false-positive deleted-surface validation for auto farfield full-body and add regression tests (#1871)

Author: benflexcompute

flow360/component/simulation/primitives.py

@@ -80,6 +80,26 @@ def _check_axis_is_orthogonal(axis_pair: Tuple[Axis, Axis]) -> Tuple[Axis, Axis]
     return (tuple(axis_1), tuple(axis_2))
 
 
+def _auto_symmetric_plane_exists_from_bbox(
+    *,
+    global_bounding_box: BoundingBoxType,
+    planar_face_tolerance: float,
+) -> bool:
+    """
+    Determine whether automated farfield logic will generate a `symmetric` plane
+    from global bounding box extents and planar-face tolerance.
+    """
+
+    y_min = global_bounding_box[0][1]
+    y_max = global_bounding_box[1][1]
+    tolerance = global_bounding_box.largest_dimension * planar_face_tolerance
+
+    positive_half = abs(y_min) < tolerance < y_max
+    negative_half = abs(y_max) < tolerance and y_min < -tolerance
+
+    return positive_half or negative_half
+
+
 OrthogonalAxes = Annotated[Tuple[Axis, Axis], pd.AfterValidator(_check_axis_is_orthogonal)]
 
 
@@ -754,6 +774,13 @@ def _will_be_deleted_by_mesher(
             if half_model_symmetry_plane_center_y is None:
                 # Legacy schema.
                 return False
+            if farfield_domain_type not in ("half_body_positive_y", "half_body_negative_y") and (
+                not _auto_symmetric_plane_exists_from_bbox(
+                    global_bounding_box=global_bounding_box,
+                    planar_face_tolerance=planar_face_tolerance,
+                )
+            ):
+                return False
             return self._overlaps(half_model_symmetry_plane_center_y, length_tolerance)
 
         if farfield_method in ("quasi-3d", "quasi-3d-periodic"):
@@ -874,12 +901,10 @@ def exists(self, validation_info) -> bool:
         if validation_info.will_generate_forced_symmetry_plane():
             return True
 
-        y_min, y_max, tolerance, _ = self._get_existence_dependency(validation_info)
-
-        positive_half = abs(y_min) < tolerance < y_max
-        negative_half = abs(y_max) < tolerance and y_min < -tolerance
-
-        return positive_half or negative_half
+        return _auto_symmetric_plane_exists_from_bbox(
+            global_bounding_box=validation_info.global_bounding_box,
+            planar_face_tolerance=validation_info.planar_face_tolerance,
+        )
 
     def _per_entity_type_validation(self, param_info: ParamsValidationInfo):
         """Validate ghost surface existence and configuration."""

tests/simulation/params/test_validators_params.py

@@ -2914,6 +2914,130 @@ def test_seedpoint_zone_based_params():
     assert errors is None
 
 
+def test_auto_farfield_full_body_surface_on_y0_not_marked_deleted():
+    surface_on_plane = Surface(
+        name="plane_surf",
+        private_attributes=SurfacePrivateAttributes(bounding_box=[[0, 0, 0], [1, 0, 1]]),
+    )
+
+    asset_cache = AssetCache(
+        project_length_unit="m",
+        use_inhouse_mesher=True,
+        use_geometry_AI=True,
+        project_entity_info=SurfaceMeshEntityInfo(
+            global_bounding_box=[[0, -2, 0], [1, 2, 1]],  # Full-body (crosses Y=0)
+            boundaries=[surface_on_plane],
+            ghost_entities=[
+                GhostSphere(
+                    name="farfield",
+                    private_attribute_id="farfield",
+                    center=[0, 0, 0],
+                    max_radius=10,
+                ),
+                GhostCircularPlane(
+                    name="symmetric",
+                    private_attribute_id="symmetric",
+                    center=[0, 0, 0],
+                    normal_axis=[0, 1, 0],
+                    max_radius=10,
+                ),
+            ],
+        ),
+    )
+
+    farfield = AutomatedFarfield()
+
+    with SI_unit_system:
+        params = SimulationParams(
+            meshing=MeshingParams(
+                defaults=MeshingDefaults(
+                    planar_face_tolerance=1e-6,
+                    geometry_accuracy=1e-5,
+                    boundary_layer_first_layer_thickness=1e-3,
+                ),
+                volume_zones=[farfield],
+            ),
+            models=[
+                Fluid(),
+                Wall(entities=[surface_on_plane]),
+                Freestream(entities=[farfield.farfield]),
+            ],
+            private_attribute_asset_cache=asset_cache,
+        )
+
+    _, errors, _ = validate_model(
+        params_as_dict=params.model_dump(mode="json"),
+        validated_by=ValidationCalledBy.LOCAL,
+        root_item_type="SurfaceMesh",
+        validation_level="All",
+    )
+
+    assert errors is None
+
+
+def test_auto_farfield_half_body_surface_on_y0_marked_deleted():
+    surface_on_plane = Surface(
+        name="plane_surf",
+        private_attributes=SurfacePrivateAttributes(bounding_box=[[0, 0, 0], [1, 0, 1]]),
+    )
+
+    asset_cache = AssetCache(
+        project_length_unit="m",
+        use_inhouse_mesher=True,
+        use_geometry_AI=True,
+        project_entity_info=SurfaceMeshEntityInfo(
+            global_bounding_box=[[0, -2, 0], [1, 2, 1]],
+            boundaries=[surface_on_plane],
+            ghost_entities=[
+                GhostSphere(
+                    name="farfield",
+                    private_attribute_id="farfield",
+                    center=[0, 0, 0],
+                    max_radius=10,
+                ),
+                GhostCircularPlane(
+                    name="symmetric",
+                    private_attribute_id="symmetric",
+                    center=[0, 0, 0],
+                    normal_axis=[0, 1, 0],
+                    max_radius=10,
+                ),
+            ],
+        ),
+    )
+
+    farfield = AutomatedFarfield(domain_type="half_body_positive_y")
+
+    with SI_unit_system:
+        params = SimulationParams(
+            meshing=MeshingParams(
+                defaults=MeshingDefaults(
+                    planar_face_tolerance=1e-6,
+                    geometry_accuracy=1e-5,
+                    boundary_layer_first_layer_thickness=1e-3,
+                ),
+                volume_zones=[farfield],
+            ),
+            models=[
+                Fluid(),
+                Wall(entities=[surface_on_plane]),
+                Freestream(entities=[farfield.farfield]),
+            ],
+            private_attribute_asset_cache=asset_cache,
+        )
+
+    _, errors, _ = validate_model(
+        params_as_dict=params.model_dump(mode="json"),
+        validated_by=ValidationCalledBy.LOCAL,
+        root_item_type="SurfaceMesh",
+        validation_level="All",
+    )
+
+    assert len(errors) == 1
+    assert errors[0]["loc"] == ("models", 1, "entities")
+    assert "Boundary `plane_surf` will likely be deleted after mesh generation." in errors[0]["msg"]
+
+
 def test_deleted_surfaces_domain_type():
     # Mock Asset Cache
     surface_pos = Surface(