Explore the mesh

This example shows how to explore and manipulate the mesh object to query mesh data such as connectivity tables, element IDs, element types and so on.

Perform required imports

Perform required imports. This example uses a supplied file that you can get by importing the DPF examples package.

from ansys.dpf import post
from ansys.dpf.post import examples
from ansys.dpf.post.common import elemental_properties

Load the result file

Load the result file in a Simulation object that allows access to the results. The Simulation object must be instantiated with the path for the result file. For example, "C:/Users/user/my_result.rst" on Windows or "/home/user/my_result.rst" on Linux.

example_path = examples.download_harmonic_clamped_pipe()
simulation = post.HarmonicMechanicalSimulation(example_path)

Get the mesh

Retrieve the mesh and print it

mesh = simulation.mesh
print(mesh)

DPF  Mesh:
  9943 nodes
  5732 elements
  Unit: mm
  With solid (3D) elements, shell (2D) elements, shell (3D) elements

Plot the mesh

Plot the mesh to view the bare mesh of the model

mesh.plot()

Query basic information about the mesh

The Mesh object has several properties allowing access to different information such as:

the number of nodes

print(f"This mesh contains {mesh.num_nodes} nodes")

This mesh contains 9943 nodes

the list of node IDs

print(f"with IDs: {mesh.node_ids}")

with IDs: [   1    2    3 ... 9941 9942 9943]

the number of elements

print(f"This mesh contains {mesh.num_elements} elements")

This mesh contains 5732 elements

the list of element IDs

print(f"with IDs {mesh.element_ids}")

with IDs [3487 3960 1449 ... 8438 8437 8540]

the unit of the mesh

print(f"The mesh is in '{mesh.unit}'")

The mesh is in 'mm'

Named selections

The available named selections are given as a dictionary with the names as keys and the actual NamedSelection objects as values. Printing the dictionary informs you on the available names.

named_selections = mesh.named_selections
print(named_selections)

NamedSelections dictionary with 4 named selections:
        - 'CLAMP'
        - 'PIPE'
        - 'SCREW'
        - '_FIXEDSU'

To get a specific named selection, query it using its name as key

print(named_selections["_FIXEDSU"])

NamedSelection '_FIXEDSU'
 with DPF  Scoping:
  with Nodal location and 161 entities

Elements

Use mesh.elements to access the list of Element objects

print(mesh.elements)

[tet10, ..., point1]

You can then query a specific element by its ID

print(mesh.elements.by_id[1])

DPF Element 1
        Index:         4239
        Nodes:           20
        Type:         Hex20
        Shape:        Solid

or by its index

element_0 = mesh.elements[0]
print(element_0)

DPF Element 3487
        Index:            0
        Nodes:           10
        Type:         Tet10
        Shape:        Solid

Query information about a particular element

You can request the IDs of the nodes attached to an Element object

print(element_0.node_ids)

[3548, 3656, 4099, 3760, 6082, 6650, 6086, 6085, 6647, 7147]

or the list of Node objects

print(element_0.nodes)

[<ansys.dpf.core.nodes.Node object at 0x7f5a4df738e0>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df72a40>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df721d0>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df728c0>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df71f90>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df70d30>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df70d90>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df71f00>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df70760>, <ansys.dpf.core.nodes.Node object at 0x7f5a4df72b00>]

To get the number of nodes attached, use

print(element_0.num_nodes)

10

Get the type of the element

print(element_0.type_info)
print(element_0.type)

Element Type
------------
Enum id (dpf.element_types): element_types.Tet10
Element description: Quadratic 10-nodes Tetrahedron
Element name (short): tet10
Element shape: solid
Number of corner nodes: 4
Number of mid-side nodes: 6
Total number of nodes: 10
Quadratic element: True
element_types.Tet10

Get the shape of the element

print(element_0.shape)

solid

Element types and materials

The Mesh object provides access to properties defined on all elements, such as their types or their associated materials.

Get the type of all elements

print(mesh.element_types)

    results elem_type_id
element_ids
       3487            0
       3960            0
       1449            0
       3131            0
       3124            0
       3126            0
        ...          ...

Get the materials of all elements

print(mesh.materials)

    results material_id
element_ids
       3487           1
       3960           1
       1449           1
       3131           1
       3124           1
       3126           1
        ...         ...

Elemental connectivity

The elemental connectivity maps elements to connected nodes, either using IDs or indexes.

To access the indexes of the connected nodes using an element’s index, use

element_to_node_connectivity = mesh.element_to_node_connectivity
print(element_to_node_connectivity[0])

[3547, 3655, 4098, 3759, 6081, 6649, 6085, 6084, 6646, 7146]

To access the IDs of the connected nodes using an element’s index, use

element_to_node_ids_connectivity = mesh.element_to_node_ids_connectivity
print(element_to_node_ids_connectivity[0])

[3548, 3656, 4099, 3760, 6082, 6650, 6086, 6085, 6647, 7147]

Each connectivity object has a by_id property which changes the input from index to ID, thus:

To access the indexes of the connected nodes using an element’s ID, use

element_to_node_connectivity_by_id = mesh.element_to_node_connectivity.by_id
print(element_to_node_connectivity_by_id[3487])

[3547, 3655, 4098, 3759, 6081, 6649, 6085, 6084, 6646, 7146]

To access the IDs of the connected nodes using an element’s ID, use

element_to_node_ids_connectivity_by_id = mesh.element_to_node_ids_connectivity.by_id
print(element_to_node_ids_connectivity_by_id[3487])

[3548, 3656, 4099, 3760, 6082, 6650, 6086, 6085, 6647, 7147]

Nodes

Get a node by its ID

node_1 = mesh.nodes.by_id[1]
print(node_1)

Node(id=1, coordinates=[44.90718016, 12.57776697, 53.33333333])

Get a node by its index

print(mesh.nodes[0])

Node(id=1, coordinates=[44.90718016, 12.57776697, 53.33333333])

Get the coordinates of all nodes

print(mesh.coordinates)

            results  coord (m)
node_ids components
       1          X 4.4907e+01
                  Y 1.2578e+01
                  Z 5.3333e+01
       2          X 4.4907e+01
                  Y 1.2578e+01
                  Z 5.1667e+01
     ...        ...        ...

Query information about one particular node

Get the coordinates of a node

print(node_1.coordinates)

[44.90718016, 12.57776697, 53.33333333]

Nodal connectivity

The nodal connectivity maps nodes to connected elements, either using IDs or indexes.

To access the indexes of the connected elements using a node’s index, use

node_to_element_connectivity = mesh.node_to_element_connectivity
print(node_to_element_connectivity[0])

[4216, 4218, 4219, 4242, 4244, 4245]

To access the IDs of the connected elements using a node’s index, use

node_to_element_ids_connectivity = mesh.node_to_element_ids_connectivity
print(node_to_element_ids_connectivity[0])

[11, 8, 14, 10, 7, 13]

Each connectivity object has a by_id property which changes the input from index to ID, thus:

To access the indexes of the connected elements using a node’s ID, use

node_to_element_connectivity_by_id = mesh.node_to_element_connectivity.by_id
print(node_to_element_connectivity_by_id[1])

[4216, 4218, 4219, 4242, 4244, 4245]

To access the IDs of the connected elements using a node’s ID, use

node_to_element_ids_connectivity_by_id = mesh.node_to_element_ids_connectivity.by_id
print(node_to_element_ids_connectivity_by_id[1])

[11, 8, 14, 10, 7, 13]

Splitting into meshes

You can split the global mesh according to mesh properties to work on specific parts of the mesh

meshes = simulation.split_mesh_by_properties(
    properties=[elemental_properties.material, elemental_properties.element_shape]
)

The object obtained is a Meshes

print(meshes)

DPF  Meshes Container
  with 14 mesh(es)
  defined on labels: elshape mat

  with:
  - mesh 0 {mat:  1, elshape:  1, } with 6673 nodes and 3517 elements.
  - mesh 1 {mat:  9, elshape:  0, } with 189 nodes and 55 elements.
  - mesh 2 {mat:  10, elshape:  0, } with 189 nodes and 55 elements.
  - mesh 3 {mat:  5, elshape:  0, } with 842 nodes and 319 elements.
  - mesh 4 {mat:  6, elshape:  0, } with 842 nodes and 319 elements.
  - mesh 5 {mat:  7, elshape:  0, } with 676 nodes and 306 elements.
  - mesh 6 {mat:  4, elshape:  1, } with 503 nodes and 72 elements.
  - mesh 7 {mat:  8, elshape:  0, } with 676 nodes and 306 elements.
  - mesh 8 {mat:  2, elshape:  1, } with 2107 nodes and 345 elements.
  - mesh 9 {mat:  3, elshape:  1, } with 658 nodes and 302 elements.
  - mesh 10 {mat:  11, elshape:  0, } with 176 nodes and 56 elements.
  - mesh 11 {mat:  16, elshape:  0, } with 97 nodes and 23 elements.
  - mesh 12 {mat:  16, elshape:  3, } with 1 nodes and 1 elements.
  - mesh 13 {mat:  12, elshape:  0, } with 176 nodes and 56 elements.

Plotting a Meshes object plots a combination of all the Mesh objects within

meshes.plot(text="Mesh split")

Select a specific Mesh in the Meshes, by index

meshes[0].plot(text="First mesh in the split mesh")

You can split the global mesh and select meshes based on specific property values

meshes_filtered = simulation.split_mesh_by_properties(
    properties={
        elemental_properties.material: [2, 3, 4],
        elemental_properties.element_shape: 1,
    }
)
meshes_filtered.plot(text="Mesh split and filtered")

or with a unique combination of property values

meshes[{"mat": 5, "elshape": 0}].plot(text="Mesh for mat=5 and elshape=0")