Feature: allow setting named dimensionless units in a Field

src/ansys/dpf/core/field.py

@@ -30,6 +30,7 @@
 
 from ansys import dpf
 from ansys.dpf.core import dimensionality, errors, meshed_region, scoping, time_freq_support
+from ansys.dpf.core.available_result import Homogeneity
 from ansys.dpf.core.common import (
     _get_size_of_list,
     locations,
@@ -617,12 +618,18 @@ def unit(self):
             return self.field_definition.unit
 
     @unit.setter
-    def unit(self, value):
+    def unit(self, value: str | tuple[Homogeneity, str]):
         """Change the unit for the field.
 
+        A single string is interpreted as a known physical unit with an associated homogeneity.
+
+        For DPF 11.0 (2026 R1) and above: A tuple of two strings is interpreted as a homogeneity and a unit name.
+            If the homogeneity is :py:attr:`Homogeneity.dimensionless`, then the unit string is kept as a name.
+            Otherwise, the homogeneity is ignored, and the unit string interpreted as a known physical unit with an associated homogeneity.
+
         Parameters
         ----------
-        value : str
+        value:
             Units for the field.
 
         Examples
@@ -635,10 +642,24 @@ def unit(self, value):
         >>> my_field.unit
         'm'
 
+
+        Named dimensionless unit.
+
+        >>> from ansys.dpf import core as dpf
+        >>> from ansys.dpf.core.available_result import Homogeneity
+        >>> my_field = dpf.Field(10)
+        >>> my_field.unit = (Homogeneity.dimensionless, "dollars")
+        >>> print(my_field.unit)
+        'dollars'
+
+        Notes
+        -----
+        Setting a named dimensionless unit requires DPF 11.0 (2026 R1) or above.
+
         """
-        fielddef = self.field_definition
-        fielddef.unit = value
-        self.field_definition = fielddef
+        field_def = self.field_definition
+        field_def.unit = value
+        self.field_definition = field_def
 
     @property
     def dimensionality(self):

src/ansys/dpf/core/field_definition.py

@@ -22,11 +22,14 @@
 
 """FieldDefinition."""
 
+from __future__ import annotations
+
 import traceback
 import warnings
 
 from ansys.dpf.core import server as server_module
-from ansys.dpf.core.check_version import version_requires
+from ansys.dpf.core.available_result import Homogeneity
+from ansys.dpf.core.check_version import server_meet_version_and_raise, version_requires
 from ansys.dpf.core.common import natures, shell_layers
 from ansys.dpf.core.dimensionality import Dimensionality
 from ansys.dpf.gate import (
@@ -204,8 +207,46 @@ def is_of_quantity_type(self, quantity_type):
         return is_of_quantity_type
 
     @unit.setter
-    def unit(self, value):
-        self._api.csfield_definition_set_unit(self, value, None, 0, 0, 0)
+    def unit(self, value: str | tuple[Homogeneity, str]):
+        """Change the unit for the field definition.
+
+        A single string is interpreted as a known physical unit with an associated homogeneity.
+
+        For DPF 11.0 (2026 R1) and above: A tuple of two strings is interpreted as a homogeneity and a unit name.
+            If the homogeneity is :py:attr:`Homogeneity.dimensionless`, then the unit string is kept as a name.
+            Otherwise, the homogeneity is ignored, and the unit string interpreted as a known physical unit with an associated homogeneity.
+
+        Parameters
+        ----------
+        value:
+            Units for the field.
+
+        Notes
+        -----
+        Setting a named dimensionless unit requires DPF 11.0 (2026 R1) or above.
+
+        """
+        # setter with explicit homogeneity: homogeneity is taken into account if it is dimensionless
+        if (
+            isinstance(value, tuple)
+            and len(value) == 2
+            and isinstance(value[0], Homogeneity)
+            and isinstance(value[1], str)
+        ):
+            server_meet_version_and_raise(
+                required_version="11.0",
+                server=self._server,
+                msg="Setting a named dimensionless unit requires DPF 11.0 (2026 R1) or above.",
+            )
+            # csfield_definition_set_unit will ignore the homogeneity if it is not dimensionless
+            self._api.csfield_definition_set_unit(self, value[1], None, value[0].value, 0, 0)
+        # standard unit setter, using string interpreter
+        elif isinstance(value, str):
+            self._api.csfield_definition_set_unit(self, value, None, 0, 0, 0)
+        else:
+            raise ValueError(
+                None, message="Unit setter supports either string or tuple(Homogeneity, str)"
+            )
 
     @location.setter
     def location(self, value):

tests/test_field.py

@@ -29,10 +29,16 @@
 from ansys import dpf
 from ansys.dpf import core
 from ansys.dpf.core import FieldDefinition, operators as ops
+from ansys.dpf.core.available_result import Homogeneity
 from ansys.dpf.core.check_version import server_meet_version
 from ansys.dpf.core.common import locations, shell_layers
+from ansys.dpf.gate.errors import DPFServerException, DpfVersionNotSupported
 import conftest
-from conftest import SERVERS_VERSION_GREATER_THAN_OR_EQUAL_TO_8_0, running_docker
+from conftest import (
+    SERVERS_VERSION_GREATER_THAN_OR_EQUAL_TO_8_0,
+    raises_for_servers_version_under,
+    running_docker,
+)
 
 
 @pytest.fixture()
@@ -1417,3 +1423,28 @@ def test_deep_copy_big_field_remote(server_type, server_type_remote_process):
 
     out = dpf.core.core._deep_copy(field_a, server_type_remote_process)
     assert np.allclose(out.data, data)
+
+
+def test_set_units(server_type):
+    data = np.random.random(100)
+    field = dpf.core.field_from_array(data)
+    # use string setter with recognized string
+    field.unit = "m"
+    assert field.unit == "m"
+
+    if server_meet_version("11.0", server_type):
+        # use tuple(Homogeneity, string) setter
+        field.unit = (Homogeneity.dimensionless, "sones")
+        assert field.unit == "sones"
+    else:
+        with pytest.raises(DpfVersionNotSupported):
+            # use tuple(Homogeneity, string) setter
+            field.unit = (Homogeneity.dimensionless, "sones")
+
+    # use unrecognized string
+    with pytest.raises(DPFServerException):
+        field.unit = "sones"
+
+    # use wrong type of arguments
+    with pytest.raises(ValueError):
+        field.unit = 1.0