Average Stress in distributed Workflows#

This example shows how stress can be read from distributed files and averaged from elemental nodal to nodal in parallel with a distributed workflow. After remote post-processing, results are merged on the local process.


This example requires the Premium ServerContext. For more information, see Server context.

Import dpf module and its examples files

from ansys.dpf import core as dpf
from ansys.dpf.core import examples
from ansys.dpf.core import operators as ops


Configure the servers#

Make a list of ip addresses and port numbers on which dpf servers are started. Workflow instances will be created on each of these servers to address each a different result file. In this example, we will post process an analysis distributed in 2 files, we will consequently require 2 remote processes. To make this example easier, we will start local servers here, but we could get connected to any existing servers on the network.

files = examples.download_distributed_files()

config = dpf.ServerConfig(protocol=dpf.server.CommunicationProtocols.gRPC)
remote_servers = [dpf.start_local_server(as_global=False, config=config) for file in files]
ips = [remote_server.ip for remote_server in remote_servers]
ports = [remote_server.port for remote_server in remote_servers]

Print the ips and ports

print("ips:", ips)
print("ports:", ports)
ips: ['', '']
ports: [50054, 50055]

Distributed Workflow#

digraph foo {
    graph [pad="0", nodesep="0.3", ranksep="0.3"]
    node [shape=box, style=filled, fillcolor="#ffcc00", margin="0"];

    stress01 [label="stress"];
    stress02 [label="stress"];
    average01 [label="elemental_nodal_to_nodal_fc"];
    average02 [label="elemental_nodal_to_nodal_fc"];

    subgraph cluster_1 {
        ds01 [label="data_src", shape=box, style=filled, fillcolor=cadetblue2];
        no_extend_to_mid_nodes01 [label="no_extend_to_mid_nodes",
                                  shape=box, style=filled, fillcolor=cadetblue2];

        ds01 -> stress01 [style=dashed];
        no_extend_to_mid_nodes01 -> stress01 [style=dashed];
        stress01 -> average01;

        label="Server 2";

    subgraph cluster_2 {
        ds02 [label="data_src", shape=box, style=filled, fillcolor=cadetblue2];
        no_extend_to_mid_nodes02 [label="no_extend_to_mid_nodes",
                                  shape=box, style=filled, fillcolor=cadetblue2];

        ds02 -> stress02 [style=dashed];
        no_extend_to_mid_nodes02 -> stress02 [style=dashed];
        stress02 -> average02;

        label="Server 1";
    merge_weighted_fields_containers [label="merge_weighted_fields_containers"];
    average01 -> merge_weighted_fields_containers;
    average02 -> merge_weighted_fields_containers;
    merge_weighted_fields_containers -> extend_to_mid_nodes;


Create a local workflow able to merge the results#

config = ops.utility.merge_weighted_fields_containers.default_config()
merge = ops.utility.merge_weighted_fields_containers(config=config)
extend_to_mid_nodes = ops.averaging.extend_to_mid_nodes_fc(merge)

Send workflows on servers#

Here we create new instances on the server by copies of the template workflow We also connect the data sources to those workflows

remote_workflows = []
for i, server in enumerate(remote_servers):
    ds = dpf.DataSources(files[i], server=server)
    stress = ops.result.stress(server=server)
    average = ops.averaging.elemental_nodal_to_nodal_fc(stress)

    merge.connect(0 + i, average.outputs.fields_container)
    merge.connect(1000 + i, average, 1)

fc = extend_to_mid_nodes.outputs.fields_container()
06 distributed stress averaging
DPF  Fields Container
  with 1 field(s)
  defined on labels: time

  - field 0 {time:  1} with Nodal location, 6 components and 432 entities.

[-1.56930398e+13 -4.83763348e+13 -1.55875426e+13 -7.69977588e+12
 -5.42547483e+12 -8.39338295e+11]
[1.56930398e+13 4.83763348e+13 1.55875426e+13 1.49730617e+12
 9.38940668e+12 8.39338295e+11]

Compare with non distributed Workflow#

Create DataSources with Domain id (one domain by distributed file).

ds = dpf.DataSources()
ds.set_domain_result_file_path(files[0], 0)
ds.set_domain_result_file_path(files[1], 1)

model = dpf.Model(ds)
stress = model.results.stress()
fc_single_process = ops.averaging.to_nodal_fc(stress).eval()

06 distributed stress averaging
[-1.56930398e+13 -4.83763348e+13 -1.55875426e+13 -7.69977588e+12
 -5.42547483e+12 -8.39338295e+11]
[1.56930398e+13 4.83763348e+13 1.55875426e+13 1.49730617e+12
 9.38940668e+12 8.39338295e+11]

Total running time of the script: ( 0 minutes 3.111 seconds)

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