[FXC-3622] Add enforced_half_model for UserDefinedFarfield and AutomatedFarfield.

flow360/component/simulation/meshing_param/volume_params.py

@@ -340,7 +340,32 @@ class RotationCylinder(RotationVolume):
     entities: EntityList[Cylinder] = pd.Field()
 
 
-class AutomatedFarfield(Flow360BaseModel):
+class _FarfieldBase(Flow360BaseModel):
+    """Base class for farfield parameters."""
+
+    enforced_half_model: Optional[Literal["+y", "-y"]] = (
+        pd.Field(  # In the future, we will support more half model types via Union.
+            None,
+            description="If set, trim to a half-model by slicing the geometry with the global Y=0 plane; "
+            "keep the '+y' or '-y' side for meshing and simulation.",
+        )
+    )
+
+    @pd.field_validator("enforced_half_model", mode="after")
+    @classmethod
+    def _validate_only_in_beta_mesher(cls, value):
+        """
+        Ensure that enforced_half_model objects are only processed with the beta mesher.
+        """
+        validation_info = get_validation_info()
+        if validation_info is None:
+            return value
+        if not value:
+            return value
+        raise ValueError("`enforced_half_model` is only supported with the beta mesher.")
+
+
+class AutomatedFarfield(_FarfieldBase):
     """
     Settings for automatic farfield volume zone generation.
 
@@ -412,7 +437,7 @@ def _validate_quasi_3d_periodic_only_in_legacy_mesher(cls, values):
         return values
 
 
-class UserDefinedFarfield(Flow360BaseModel):
+class UserDefinedFarfield(_FarfieldBase):
     """
     Setting for user defined farfield zone generation.
     This means the "farfield" boundaries are coming from the supplied geometry file

flow360/component/simulation/translator/surface_meshing_translator.py

@@ -147,6 +147,17 @@ def _get_surface_refinements(refinement_list: list[dict]):
     ]
 
 
+def _get_volume_zones(volume_zones_list: list[dict]):
+    """
+    Get the volume zones from the input_params.
+    """
+    return [
+        item
+        for item in volume_zones_list
+        if item["type"] in ("AutomatedFarfield", "UserDefinedFarfield")
+    ]
+
+
 GAI_SETTING_WHITELIST = {
     "meshing": {
         "defaults": {
@@ -159,6 +170,7 @@ def _get_surface_refinements(refinement_list: list[dict]):
             "surface_max_adaptation_iterations": None,
         },
         "refinements": _get_surface_refinements,
+        "volume_zones": _get_volume_zones,
     },
     "private_attribute_asset_cache": {
         "project_entity_info": {

flow360/component/simulation/translator/volume_meshing_translator.py

@@ -261,6 +261,8 @@ def get_volume_meshing_json(input_params: SimulationParams, mesh_units):
     for zone in input_params.meshing.volume_zones:
         if isinstance(zone, UserDefinedFarfield):
             translated["farfield"] = {"type": "user-defined"}
+            if zone.enforced_half_model is not None:
+                translated["farfield"]["enforcedHalfModel"] = zone.enforced_half_model
             break
 
         if isinstance(zone, AutomatedFarfield):
@@ -272,6 +274,9 @@ def get_volume_meshing_json(input_params: SimulationParams, mesh_units):
                 translated["farfield"]["periodic"] = {"type": "translational"}
             else:
                 translated["farfield"]["type"] = zone.method
+
+            if zone.enforced_half_model is not None:
+                translated["farfield"]["enforcedHalfModel"] = zone.enforced_half_model
             break
 
     if "farfield" not in translated:

tests/simulation/params/meshing_validation/test_meshing_param_validation.py

@@ -454,3 +454,13 @@ def test_quasi_3d_periodic_only_in_legacy_mesher():
     # does not raise with legacy mesher on
     with ValidationContext(VOLUME_MESH, non_beta_mesher_context):
         my_farfield = AutomatedFarfield(method="quasi-3d-periodic")
+
+
+def test_enforced_half_model_only_in_beta_mesher():
+    # raises when beta mesher is off
+    with pytest.raises(
+        pd.ValidationError,
+        match=r"`enforced_half_model` is only supported with the beta mesher.",
+    ):
+        with ValidationContext(VOLUME_MESH, non_beta_mesher_context):
+            AutomatedFarfield(enforced_half_model="+y")

tests/simulation/translator/ref/surface_meshing/gai_surface_mesher.json

@@ -184,6 +184,15 @@
                     "units": "flow360_length_unit"
                 }
             }
+        ],
+        "volume_zones": [
+            {
+                "enforced_half_model": "+y",
+                "type": "AutomatedFarfield",
+                "name": "Automated Farfield",
+                "method": "auto",
+                "relative_size": 50.0
+            }
         ]
     },
     "private_attribute_asset_cache": {
@@ -631,4 +640,4 @@
             ]
         }
     }
-}
+}

tests/simulation/translator/test_surface_meshing_translator.py

@@ -527,7 +527,7 @@ def test_gai_surface_mesher_refinements():
         )
         geometry["cube-holes.egads"].transformation = transformation
         geometry["cylinder.stl"].transformation = transformation
-        farfield = AutomatedFarfield()
+        farfield = AutomatedFarfield(enforced_half_model="+y")
         params = SimulationParams(
             meshing=MeshingParams(
                 defaults=MeshingDefaults(

tests/simulation/translator/test_volume_meshing_translator.py

@@ -183,7 +183,7 @@ def get_test_param():
                             Surface(name="interface2"),
                         ],
                     ),
-                    UserDefinedFarfield(),
+                    UserDefinedFarfield(enforced_half_model="-y"),
                     RotationVolume(
                         name="we_do_not_use_this_anyway",
                         entities=inner_cylinder,
@@ -248,7 +248,7 @@ def test_param_to_json(get_test_param, get_surface_mesh):
 
     ref_dict = {
         "refinementFactor": 1.45,
-        "farfield": {"type": "user-defined"},
+        "farfield": {"type": "user-defined", "enforcedHalfModel": "-y"},
         "volume": {
             "firstLayerThickness": 1.35e-06,
             "growthRate": 1.04,