feat: Retrieve mesh data in solution mode (#3618)

* feat: Retrieve mesh data in solution mode

* feat: Retrieve mesh data in solution mode

* build: update ansys-api-fluent version

* test: mesh data

* feat: unsort element data

* test: fix

* test: fix

pyproject.toml

@@ -20,7 +20,7 @@ classifiers = [
     "Operating System :: OS Independent",
 ]
 dependencies = [
-    "ansys-api-fluent>=0.3.30",
+    "ansys-api-fluent>=0.3.31",
     "ansys-platform-instancemanagement~=1.0",
     "ansys-tools-filetransfer>=0.1,<0.3",
     "ansys-units>=0.3.3,<0.5",

src/ansys/fluent/core/services/field_data.py

@@ -1,7 +1,9 @@
 """Wrappers over FieldData gRPC service of Fluent."""
 
+from dataclasses import dataclass
 from enum import Enum
 from functools import reduce
+import io
 from typing import Callable, Dict, List, Tuple
 
 import grpc
@@ -82,6 +84,36 @@ def get_fields(self, request):
             )
         return chunk_iterator
 
+    def get_solver_mesh_nodes(
+        self, request: FieldDataProtoModule.GetSolverMeshNodesRequest
+    ):
+        """GetSolverMeshNodesDouble RPC of FieldData service."""
+        chuncked_responses = self._stub.GetSolverMeshNodesDouble(
+            request, metadata=self._metadata
+        )
+        buffer = io.BytesIO()
+        for chuncked_response in chuncked_responses:
+            buffer.write(chuncked_response.chunk)
+        serialized_response = buffer.getvalue()
+        response = FieldDataProtoModule.GetSolverMeshNodesDoubleResponse()
+        response.ParseFromString(serialized_response)
+        return response
+
+    def get_solver_mesh_elements(
+        self, request: FieldDataProtoModule.GetSolverMeshElementsRequest
+    ):
+        """GetSolverMeshElements RPC of FieldData service."""
+        chuncked_responses = self._stub.GetSolverMeshElements(
+            request, metadata=self._metadata
+        )
+        buffer = io.BytesIO()
+        for chuncked_response in chuncked_responses:
+            buffer.write(chuncked_response.chunk)
+        serialized_response = buffer.getvalue()
+        response = FieldDataProtoModule.GetSolverMeshElementsResponse()
+        response.ParseFromString(serialized_response)
+        return response
+
 
 class FieldInfo:
     """Provides access to Fluent field information.
@@ -922,6 +954,89 @@ def _extract_field(field_datatype, field_size, chunk_iterator):
         return fields_data
 
 
+@dataclass
+class Node:
+    """Node class for mesh.
+
+    Attributes:
+    -----------
+    x : float
+        x-coordinate of the node.
+    y : float
+        y-coordinate of the node.
+    z : float
+        z-coordinate of the node.
+    """
+
+    _id: int
+    x: float
+    y: float
+    z: float
+
+
+class CellElementType(Enum):
+    """Element types for a cell element."""
+
+    # 3 nodes, 3 faces
+    TRIANGLE = 1
+    # 4 nodes, 4 faces
+    TETRAHEDRON = 2
+    # 4 nodes, 4 faces
+    QUADRILATERAL = 3
+    # 8 nodes, 6 faces
+    HEXAHEDRON = 4
+    # 5 nodes, 5 faces
+    PYRAMID = 5
+    # 6 nodes, 5 faces
+    WEDGE = 6
+    # Arbitrary number of nodes and faces
+    POLYHEDRON = 7
+    # 2 nodes, 1 face (only in 2D)
+    GHOST = 8
+    # 10 nodes, 4 faces
+    QUADRATIC_TETRAHEDRON = 9
+    # 20 nodes, 6 faces
+    QUADRATIC_HEXAHEDRON = 10
+    # 13 nodes, 5 faces
+    QUADRATIC_PYRAMID = 11
+    # 15 nodes, 5 faces
+    QUADRATIC_WEDGE = 12
+
+
+@dataclass
+class Element:
+    """Element class for mesh.
+
+    Attributes:
+    -----------
+    element_type : CellElementType
+        Element type of the element.
+    node_indices : list[int]
+        0-based node indices of the element.
+    """
+
+    _id: int
+    element_type: CellElementType
+    node_indices: list[int]
+
+
+@dataclass
+class Mesh:
+    """Mesh class for Fluent field data.
+
+    Attributes:
+    -----------
+    nodes : list[Node]
+        List of nodes in the mesh. Sorted by Fluent's node ID.
+    elements : list[Element]
+        List of elements in the mesh. Unsorted as we want to correlate with the
+        solution data retrieved via svar service.
+    """
+
+    nodes: list[Node]
+    elements: list[Element]
+
+
 class FieldData:
     """Provides access to Fluent field data on surfaces."""
 
@@ -1285,3 +1400,38 @@ def get_pathlines_field_data(
                 field_name: pathlines_data[surface_ids[count]][field_name],
             }
         return path_lines_dict
+
+    def get_mesh(self, zone_id: int) -> Mesh:
+        """Get mesh for a zone.
+
+        Parameters
+        ----------
+        zone_id : int
+            Zone ID.
+
+        Returns
+        -------
+        Mesh
+            Mesh object containing nodes and elements.
+        """
+        request = FieldDataProtoModule.GetSolverMeshNodesRequest(
+            domain_id=1, thread_id=zone_id
+        )
+        response = self._service.get_solver_mesh_nodes(request)
+        nodes = response.nodes
+        nodes = [Node(_id=node.id, x=node.x, y=node.y, z=node.z) for node in nodes]
+        nodes = sorted(nodes, key=lambda x: x._id)
+        request = FieldDataProtoModule.GetSolverMeshElementsRequest(
+            domain_id=1, thread_id=zone_id
+        )
+        response = self._service.get_solver_mesh_elements(request)
+        elements = response.elements
+        elements = [
+            Element(
+                _id=element.id,
+                element_type=CellElementType(element.element_type),
+                node_indices=[(id - 1) for id in element.node_ids],
+            )
+            for element in elements
+        ]
+        return Mesh(nodes=nodes, elements=elements)

tests/test_field_data.py

@@ -1,10 +1,15 @@
 import numpy as np
 import pytest
+from test_utils import pytest_approx
 
 from ansys.fluent.core import examples
 from ansys.fluent.core.examples.downloads import download_file
 from ansys.fluent.core.exceptions import DisallowedValuesError
-from ansys.fluent.core.services.field_data import FieldUnavailable, SurfaceDataType
+from ansys.fluent.core.services.field_data import (
+    CellElementType,
+    FieldUnavailable,
+    SurfaceDataType,
+)
 
 HOT_INLET_TEMPERATURE = 313.15
 
@@ -464,3 +469,19 @@ def plot_mesh(index, field_name, data):
     assert len(mesh_data[5]["faces"]) == 80
 
     assert list(mesh_data[12].keys()) == ["vertices", "faces"]
+
+
+@pytest.mark.fluent_version(">=25.2")
+def test_mesh_data(static_mixer_case_session):
+    solver = static_mixer_case_session
+    mesh = solver.fields.field_data.get_mesh(zone_id=97)
+    assert len(mesh.nodes) == 82247
+    assert len(mesh.elements) == 22771
+    assert mesh.elements[0].element_type == CellElementType.POLYHEDRON
+    assert len(mesh.elements[0].node_indices) > 0
+    assert min(mesh.nodes, key=lambda x: x.x).x == pytest_approx(-1.999075e-03)
+    assert max(mesh.nodes, key=lambda x: x.x).x == pytest_approx(1.999125e-03)
+    assert min(mesh.nodes, key=lambda x: x.y).y == pytest_approx(-3.000000e-03)
+    assert max(mesh.nodes, key=lambda x: x.y).y == pytest_approx(3.000000e-03)
+    assert min(mesh.nodes, key=lambda x: x.z).z == pytest_approx(-2.000000e-03)
+    assert max(mesh.nodes, key=lambda x: x.z).z == pytest_approx(2.500000e-03)