How to compare two transient runs and extract maximum of difference between nodal temperatures?

Pierre Thieffry

We want to compare two thermal transient runs, under the assumption they contain results at the exact same time steps. As an end result, we want to get a plot of the maximum differences between nodal results over the entire time range - i.e. we only have one plot showing max(t2,t1) not at every time step but for the entire time range.

Who wants to try?

Pierre Thieffry

Here’s a first solution, yet a bit tedious. I could not find a way to use the “minus” operator on fields_container with more than one field

# Perform a comparison between two thermal transient runs
# End result: a plot of the maximum differences over the full time range between the two runs for each node
# V1: investigate by time step
# Important: It is assumed both thermal results have been computed at the same time points

import mech_dpf
import Ans.DataProcessing as dpf

import time

time0=time.time()
dataSource_th1 = dpf.data.DataSources() 
dataSource_th2 = dpf.data.DataSources() 

#please set the result file path to the right path
dataSource_th1.SetResultFilePath(r'C:\temp\SAE\ComparaisonThermiques_files\dp0\SYS\MECH\file.rth','rth')
dataSource_th2.SetResultFilePath(r'C:\temp\SAE\ComparaisonThermiques_files\dp0\SYS-1\MECH\file.rth','rth')


timePointsOp =dpf.operators.metadata.time_freq_provider()
timePointsOp.inputs.data_sources.Connect(dataSource_th1)

timepoints=dpf.data.Scoping()
timepoints.Ids=range(1,timePointsOp.outputs.time_freq_support.GetData().TimeFreqs.Data.Count+1)
timepoints.Location="Time"

t1 = dpf.operators.result.temperature()
t2 = dpf.operators.result.temperature()

tdisplay = dpf.operators.result.temperature()
tdisplay.inputs.data_sources.Connect(dataSource_th1)

t1.inputs.data_sources.Connect(dataSource_th1)
t2.inputs.data_sources.Connect(dataSource_th2)

t1.inputs.time_scoping.Connect(timepoints)
t2.inputs.time_scoping.Connect(timepoints)

tempdiff=t1 # copy from t1 to initialize data

squareop = dpf.operators.math.sqr() # operator instanciation
sqrtop= dpf.operators.math.sqrt()
# Compute difference between t2 and t1 for each time steps, store in tempdiff
for i in timepoints.Ids:
    tempdiff_t=dpf.operators.math.minus()
    tempdiff_t.inputs.fieldA.Connect(t2.outputs.fields_container.GetData()[i-1])
    tempdiff_t.inputs.fieldB.Connect(t1.outputs.fields_container.GetData()[i-1])
    squareop.inputs.field.Connect(tempdiff_t.outputs.field)
    sqrtop.inputs.field.Connect(squareop.outputs.field)
    tempdiff.outputs.fields_container.GetData()[i-1].Data = sqrtop.outputs.field.GetData().Data

# Compute max over time
tempDiffMax=tempdiff.outputs.fields_container.GetData()[0] # Retrieve Field for first time step
for i in timepoints.Ids: # For each time point, compare existing max with time point and update data if needed
    actualMaxData=tempDiffMax.Data
    candidateMaxData=tempdiff.outputs.fields_container.GetData()[i-1].Data
    nbData=actualMaxData.Count
    for j in range(0,nbData): # Loop over nodes
        actualMax=actualMaxData[j]
        candidateMax=candidateMaxData[j]
        if actualMax<candidateMax:
            actualMaxData[j]=candidateMax
    tempDiffMax.Data=actualMaxData

time1=time.time()

print ('Evaluation over all time steps performed in :',time1-time0,'s')

tdisplay.outputs.fields_container.GetData()[0].Data=tempDiffMax.Data

wf = dpf.data.Workflow()
wf.Add(tdisplay)
wf.SetOutputContour(tdisplay)

wf.Record("wf_id", True)

M

@Pierre Thieffry If you want to compare max values, I put together a script to do that: https://discuss.ansys.com/discussion/2514/model-statistical-result-comparison-using-pydpf/p1?new=1